What firmware are you programming onto the devices? I could try getting one of my MG24’s into a similar state to try see what is going on?
I can generally still modify (Non volatile “flash” memory) on an MG24 down to 1.8V (lower possible but risky).
EEProm - not sure what you mean by this? Do you have separate EEProm on the device? Or did you mean the on-board flash?