No don't do that
I flashed My Archer C20 to use Wireguard !!!! When I tried to recover original firmware,I bricked it ! I flashed it Via Programmer Now it doesn't work anymore,router doesn't turn on
I don't know what to do 
it's tftp recovery flash is literally a trap.
- it needs special image different from gui/sysupgrade image
- if you don't use it, it will overwrite the bootloader and you need spi clip to recover it