I believe my RepRap is RepRap Prusa Mendel Iteration 2 using a Printrboard which the firmware won't reload for some reason.
https://photos.app.goo.gl/bRiPc2Q5pxmSzQYJ7
Documentation
Flashed firmware with:
sudo avrdude -c usbtiny -p at90usb1286 -U flash:w:BootloaderHID.hex:i
sudo /home/pi/work/arduino-1.8.16/hardware/printrboard/avr/tools/hid_bootloader_cli -v -mmcu=at90usb1286 -w Sprinter.cpp.hex