How To Reflash Factory Firmware on the NETGEAR WRN3500L Without A Serial Cable

When you upgrade to DD-WRT on your WNR3500L, you'll find that the new firmware requires a file that ends with the BIN extension, if you ever want to upgrade or change your firmware from that point.

So, if you decide, for example, to revert back to the original NETGEAR firmware - you can't because that firmware has a filename that ends in CHK.

As such, this makes it harder to change back. One way to do it is to use a serial console, but if you don't have one... here's a way to accomplish it in Windows without one.

Fortunately, included in the DD-WRT firmware is an erase utility that will wipe the firmware and allow you to upload a new one.

Here is how it's done.

You first have to Telnet into your router.

To do this simply open up a CMD window and type Telnet 192.168.1.1 (or the location of your router)

You will then need to type in the name and password for your router. If you have not changed it form the original setup, then they would be Name:admin and Password:password.

Once in, you will be shown a prompt that you can use to erase the old firmware.

Type in "erase linux" and it will run and show you its progress.

Once complete, it will again show you a command prompt.

Type in "reboot" and you should see "Connection to host lost"

You can then close this window.

Now we need to put the new firmware on.

Wait about 5 minutes for the router to reboot and then open up a new CMD window.

You will then use TFTP to put the new firmware on the router. This program comes with Windows XP. If you are using Vista, you need to install it.

1. Open the Control Panel and select the Programs entry.
2. From the Programs and Features section, select Turn Windows features on or off.

3. Scroll down the list and place a check in the box next to TFTP Client. Click OK.

4. Give Windows a moment or three to install the tftp client. When its done, exit out of the Control Panel.

Open up a CMD window and type in "tftp -i 192.168.1.1 PUT NameOfFirmware.CHK" as shown below.

Wait a few minutes and you should see "Transfer Successful"

At this point all you need to do is wait. The router will install the firmware and reboot automatically. This could take 5 to 10 minutes.

Once the router is finished booting you can go back into your browser and setup your desired configuration.

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deltoid
deltoid's picture
nice one.... very good step

nice one.... very good step-by-step tutorial

deltoid
deltoid's picture
can you not run "erase linux"

can you not run "erase linux" from dd-wrt's command web ui?

Heintz
Heintz's picture
Unfortunately did this

Unfortunately did this tutorial brick my router... :-(

I ran "erase linux" and "reboot" and after the router rebooted I couldn't connect to it anymore (no DHCP lease) and the power led blinks (green).

I'll see what happens if I assign a static IP and gateway, but my hopes aren't up...

Anyone ideas accept waiting for the USB-TTL cable and follow the debrick procedure?

Update: Static IP & Gateway did the trick! A good idea would be to update the tutorial with that information. When the router reboots the attached PC will try to obtain a new IP using DHCP (which didn't work in my case) thus assigning the "couldn't get a IP"-address 169.x.x.x and therefore I was unable to tftp to 192.168.1.1.

gab
gab's picture
Will adding DD-wrt or 3rd

Will adding DD-wrt or 3rd party fw to this router void my warranty????

mischief1
mischief1's picture
I recently did all of this

I recently did all of this but at the last step its saying it timed out.
I have Windows 7 ultimate 64 running XP virtual mode

ajhawley
ajhawley's picture
DINT WORK ROUTER POWER LIGHT

DINT WORK ROUTER POWER LIGHT FLASHES GREEN AND THE FIRMWARE DOES NOT FLASH CAN SOME ONE PLEASE ADVISE ME ON WHATTO DO NEXT

kosskossy
kosskossy's picture
If the router lights flash

If the router lights flash green, just send the stock firmware twice in a row i.e. put the same command [tftp -i 192.168.1.1 PUT firmware.chk) through a second time. You can do this by hitting the "up" arrow and then hitting "Enter"

Hope this helps... Good Luck

ajhawley
ajhawley's picture
am sure i tried this i also

am sure i tried this i also tried to send wrt back but was a no go phoned them and got it rma'd cost me £3 to send it back recorded

tsanga
tsanga's picture
I did erase linux and tried

I did erase linux and tried to tftp but it wouldn't take. Basically there's no OS on the router.

My WNR3500v2 successfully accepts tftp after tftp without doing anything, always returning to flashing green power LED.

I've tried two different revs of Netgear factory firmware, I've tried the two files listed in the DD-WRT router database for WNR3500v2, and I've tried teddy_bear's Tomato beta. The factory files successfully complete tftp but nothing happens. The other ones cause the router to go offline, and after waiting a long time, I reset it only to come back to a continuously blinking green power LED.

Ping continuously returns TTL=100 which I read to mean it's ready for tftp.

I've also tried shorting the two pins to reset the NVRAM as posted by fabien somewhere on this site.

Help?

DomiNET
DomiNET's picture
It worked great for me, no

It worked great for me, no flashing green light and the router works fine with one exception:

- I can't log in on the router. Have tried admin & password, root & admin and all other combinations of usernames and password that I used during my 1-day dd-wrt era. Turned the thing off and resetted to factory settings and tried the above usernames and passwords again. Still no access.

Any ideas anyone?

Update: A Hard Reset did the job. The reset I mentioned above was not according the the "simple reset" or "30-30-30 reset" described elsewhere in this forum.

creaturecool
creaturecool's picture
So does this process require

So does this process require that the user assigns a static IP address to their own computer in order to perform the reflash? (if so, how does one do so?)
I'm trying to get back to factory firmware after trying a version of DD-WRT on this site that isn't nearly as stable as the factory original.

creaturecool
creaturecool's picture
also, do you have to specify

also, do you have to specify the directory where the factory firmware is located?

kosskossy
kosskossy's picture
Here is what I did to get

Here is what I did to get mine to work

-Downlaod the latest firmware from netgear and rename it to WNR3500.chk
-Save it on your C drive
-Open cmd
-Type "cd\" and hit "enter", this will move you to the C drive
-Type "tftp -i 192.168.1.1 PUT WNR3500.chk" DON'T PRESS "ENTER"
-Now plug in the power to your router while holding a screw driver in your hand
-wait until all lights flashes and then short the 2 pins shown in Fabian pic
-while having your screwdriver on the 2 pins, go to the cmd window and press"ENTER"
- wait until you get a confirmation that the file transferred sucessfuly==> Then my lights started blinking green==>
-Now put your screwdriver on the table and press the "upward" arrow and then press "enter" to send the firmware file a second time.

- The light color will change from blinking green to blinking orange... wait... wait... wait... wait 5 minutes and the router will be restored.

creaturecool
creaturecool's picture
Alright! I completed the

Alright! I completed the flash successfully!
I followed the steps above, and when it came time to tftp the router I changed directories in cmd to where I had the router firmware stored, then tftp'd it. I also made sure to assign a static IP to my computer before doing this. I think these are some crucial steps that should be added to this post to ensure clarity and allow everyone to successfully complete the flash.

Matt Mueller
Matt Mueller's picture
http://www.youtube.com/watch
kosskossy
kosskossy's picture
I think you will find this
buddee
buddee's picture
edoc said: That's the article

edoc said: That's the article that relies upon a MS version of windows. I do not use any MS products, only Linux, which is a major reason I bought a WNR3500L. I need a MS-free solution, please?

Simply use tftp from a linux terminal, yes the above process is shown with a windows command prompt, but tftp is in linux as well.

NathanF
NathanF's picture
Two notes for anyone having

Two notes for anyone having issues:

Before doing this procedure, make sure the IP of the router is 192.168.1.1! I had changed mine to something custom, but it would only allow me to tftp to 192.168.1.1, which meant I had to assign a static ip locally, yadda yadda.

Also strange, after restoring the factory firmware it went back to my custom IP, but I could not login. A hard reset (via the button) fixed that.

Roy519
Roy519's picture
Follow the tutorial from the

Follow the tutorial from the link below

works perfectly

Good job Matt

http://www.youtube.com/watch?v=dfry1lmlWg4

Matt Mueller
Matt Mueller's picture
Thanks!

Thanks!

taekwon3dan
taekwon3dan's picture
This procedure has worked for

This procedure has worked for me 2 out of 2 times (and confirmed by another member) to flash Netgear stock firmware back from Tomato 9047:

This is what I did going from tomato 9047 to Netgear 1.0.2.50. After a 30-30-30, I simply upgraded to Netgear 1.0.2.50 in chk format. It took, but the power light keeps blinking.

At this point, I power cycled (30 sec), did 30-30-30, and then tftp'd to 192.168.1.1 [ tftp -i 192.168.1.1 put filenameofnetgearfirmware] (NOTE: I HAVE ALSO SUCCEEDED EVEN WHEN YOU SKIP THE POWER CYCLE AND 30-30-30. JUST TFTP DIRECTLY.)

Wait 5 minutes, power cycle, 30-30-30...VOILA.

IN MY EXPERIENCE, IT IS IMPORTANT THAT YOU SET A STATIC IP ON YOUR PC WHEN PLAYING AROUND WITH ROUTER FIRMWARE UPGRADES!!

sigman
sigman's picture
@Heintz, got exactly the same

@Heintz, got exactly the same problem. I didn't actually figure out that I need to set a static ip on my PC after erasing DD-WRT.

But I was able to re-flash it from that point back to the original firmware using "Firmware recovery utility" that is on the bundled CD.

I think this whole process of re-flashing could be done from very beginning using that Netgear's recovery utility rather than telnet-ing and tftp-ing... I presume it's just does all these steps from tutorial in the background. Am I right?

lijinting
lijinting's picture
And if you're a girl on the

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wyse
wyse's picture
taekwon3dan said: This

taekwon3dan said: This procedure has worked for me 2 out of 2 times (and confirmed by another member) to flash Netgear stock firmware back from Tomato 9047: This is what I did going from tomato 9047 to Netgear 1.0.2.50. After a 30-30-30, I simply upgraded to Netgear 1.0.2.50 in chk format. It took, but the power light keeps blinking. At this point, I power cycled (30 sec), did 30-30-30, and then tftp'd to 192.168.1.1 [ tftp -i 192.168.1.1 put filenameofnetgearfirmware] Wait 5 minutes, power cycle, 30-30-30...VOILA. IN MY EXPERIENCE, IT IS IMPORTANT THAT YOU SET A STATIC IP ON YOUR PC WHEN PLAYING AROUND WITH ROUTER FIRMWARE UPGRADES!!

ok, works fine from tomatoUSB 9049 to Netgear 1.0.2.50, no problem.

Thanks

aloa from paris

 

dmlogs
dmlogs's picture
Followed the same steps on

Followed the same steps on Mac OSX using telnet and tftp utilities in terminal. Worked perfectly.

If anyone is interested here are the screenshots: http://dmlogs.imgur.com/flash_to_factory_firmware_wnr3500l

josip
josip's picture
I tried to do this in linux.

I tried to do this in linux.

After the "reboot" command I tried to tftp but apparently the commands aren't the same and I couldn't get it to work.

I eventually gave up trying to upload the new firmware and pinged the router. Over many trials, 30-30-30 resets, and more, it didn't reply to the ping. What can I do!?!

fjl307
fjl307's picture
kosskossy said: Here is what

kosskossy said: Here is what I did to get mine to work -Downlaod the latest firmware from netgear and rename it to WNR3500.chk -Save it on your C drive -Open cmd -Type "cd\" and hit "enter", this will move you to the C drive -Type "tftp -i 192.168.1.1 PUT WNR3500.chk" DON'T PRESS "ENTER" -Now plug in the power to your router while holding a screw driver in your hand -wait until all lights flashes and then short the 2 pins shown in Fabian pic -while having your screwdriver on the 2 pins, go to the cmd window and press"ENTER" - wait until you get a confirmation that the file transferred sucessfuly==> Then my lights started blinking green==> -Now put your screwdriver on the table and press the "upward" arrow and then press "enter" to send the firmware file a second time. - The light color will change from blinking green to blinking orange... wait... wait... wait... wait 5 minutes and the router will be restored.

I did this, minus all the shorting stuff. In addition, I also assigned a static IP to my NIC. Some of the other comments on this page explain how to do that. 

Melmacj
Melmacj's picture
If you keep getting a

If you keep getting a flashing green light and the tftp command is not working. I have the most easiest fix. Just pop the CD in your PC. Have that ethernet cable still hook up. set IP 192.168.1.8, 255.255.255.0, 192.168.1.1 is default gateway. Run the recovery utilty from the CD and it'll put eveything back like it was. You may still have to do up to the erase linux part of this tutorial but after that the CD will take it from there if you run into problems. Hope this helps. It help me.

rupert
rupert's picture
hi, if you are on a MAC you

hi, if you are on a MAC you can use MacTFTP to upload the original FW to the router. The tftp program on Mac OS X doesn't word with the "-i" option, so it is easier to use MacTFTP.

Get it here:
http://www.macupdate.com/info.php/id/12146/mactftp-client

Btw. I had to turn off/on the router to get the router to accept the incoming FW.

rupert
rupert's picture
If you are on Mac OS X you

If you are on Mac OS X you can use a small TFTP client to upload the FW to the router. The original tftp program on the Mac doesn't accept the "-i" option and didn't seem to work for me.

http://www.macupdate.com/info.php/id/12146/mactftp-client

PS I had to restart the router after the "reboot" to get it to accept the upload.

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