Bricked R7000, Can't Connect with Serial -- HELP?

Hello! I'm pretty new to this, so please don't hesitate to ask for clarification if I fail to properly explain anything.

I tried flashing Fresh Tomato to my R7000, and immediately bricked it. I can't connect through ethernet nor wifi (no wifi networks show), and I can't get to 192.168.1.1. Tried the 30/30/30 reset, and nothing changed. So I ordered a usb-ttl adapter (this one), connected it up to the router, and tried to connect with PuTTY in Windows 10, and with Minicom in Ubuntu... but I get nothing from the router when I try powering it on. Like, literally nothing comes on screen from those programs.

So now I'm at a loss... can anyone recommend other steps to take? I can't really afford to replace the router, and I don't want to be stuck with my ISP's router/modem as I am currently.

Thanks in advance!