I just checked with avrdude (on Linux), and I had no difficulties with pinging the device, backing up, and updating, while using the instructions over at https://anduril.click/flashing/avrdude.html.

SOLVED!

Thank you very much!

I was able to successfully ping and backup eeprom and hex file from my D2 with the following commands:

ping:

avrdude -p t1634 -c usbasp -n

backup eeprom:

avrdude -p t1634 -c usbasp -U eeprom:r:desktop/D2eeprom-backup.hex:i

backup D2 stock hex:

avrdude -p t1634 -c usbasp -U flash:r:desktop/oldD2-firmware.hex:i

Thanks!