Most likely that the two CR2450 batteries in the PCI card are dead. So the NVRAM is corrupt now.
To fix it, replace those two batteries, boot with the ekey7 & diag key and clear NVRAM and Safe Storage ONLY. If you don't have an ekey7 and diag key, there's little you can do.
Then reboot with no keys plugged in You'll get prompted to complete initial setup, but existing games will remain on the machine. You'll just need to re-enable them after completing initial machine setup.
If you're replacing batteries, it's also a good idea to replace the CR2032 battery in the motherboard as well, as you'll reset the correct time/date when you complete initial setup after clearing the NVRAM.
Should put it back in service. Those batteries generally last many years, but they do eventually go below min voltage which loses the NVRAM data requiring a reset like that after replacing the batteries.