i would wipe the rrg repo entirely from proxspace… then do another git clone… update the Makefile.platform to PLATFORM=PM3OTHER and do a total make clean && make all and then make install … then hold the flash button down, plug in, run ./pm3-flash-bootrom with the button held down the whole time… let it finish… release the button… let it sit for 30 seconds… then unplug USB… then plug it back in with the button held (again) and do the ./pm3-flash-fullimage … release… 30 seconds… unplug USB… plug back in… then wait a good 60 seconds and see if it comes back online.
I have an old rysc corp proxmark3 original board i just did this to and it had some hiccups but finally after following the above it worked.