In this video I demonstrate how to identify and flash the stock ROM back onto a modified GPU that was previously used for cryptocurrency mining. Also what might go wrong along the way...
GPUZ:
https://www.techpowerup.com/gpuz//
ATIFlash:
https://www.techpowerup.com/download/ati-atiflash/
GPU BIOS list:
https://www.techpowerup.com/vgabios/