Just a hint: I debricked my C2's via CH341A. You do not need to de-solder flash memory from board in order to flash it. Actually, de-soldering is very hard to do (I destroyed one of my routers trying to remove flash chip). I was able to both read and write C2 flash in-situ, while soldered. Red wire needs to go on the dot. Router should be disconnected from power.
That being said, C2 is a bad router for OpenWRT. Only 5GHz is usable as 2.4GHz driver is buggy and will fold under heavy usage. See my thread here: Archer C2: 2.4GHz (MT7620) support is broken
I have since replaced all my C2's for C7's. Much better throughput on 5GHz and also better radio.