Due to lack of stock firmware documentation on the wiki, I accidentally tried to flash the latest firmware through TFTP without stripping it. After a few unsuccessful tries, the router eventually 'bricked'.
The Archer C7 v4 only boots with a solid power LED and when attempting to enter TFTP mode by holding reset when booting, the power LED solid but the reset(?) LED appears solid for a couple seconds and then turns off leaving you with just the solid power LED. Normally when entering TFTP mode, after the reset(?) LED turns off, the power LED will begin blinking which means it has entered TFTP mode.
I already have a RPi 3 and a cheap breadboard kit on the way since I need some of it for a few other projects anyway.
Will I be able recover using serial (tpl/u-boot) without TFTP mode? If not, are there instructions on manually flashing the chip (Winbond W25Q64FV?) using something such as flashrom?
You'll have to wait and see what it says via serial, everything else is guesswork at this point.
If you damaged the bootloader (which is likely, if tftp is no longer available), it's game over (well, at least from an economic point of view, as recovering that would involve soldering, flashing via SPI, etc.) - if you overwrote the wifi calibration data (ART), which is almost certain, the WLAN functionality will cease to exist (permanently). But it all depends on how badly you damaged it - and that's what serial console access should tell you.
Figured that would be probably be the case, although I'll still give serial a shot. Out of curiosity, any idea if anyone has documented flashing via SPI for this particular chip?
SPI NOR chips are pretty much the same (at least up to and including 16 MB), aside from soldering and necessary equipment that isn't the problem - but you can only hope that you can still recover a functional ART from the chip before reflashing it.