iMac G3 tray "NVRAM Partition invalid (bad checksum)" error

[indibil]

Hi, I'm working on this iMac and, even though I put a new battery in it, every time I start it up it shows me this message on the screen, along with the folder symbol with a question mark, and after a few seconds it boots from the first partition.

Even if I select another partition in the boot menu, it doesn't save, it always shows this message and seems to search again. I tell you that booting with the ALT key doesn't work, it ignores it, only pressing C or pressing O+F+Alt+Option works.

Within Open Firmware I apply the commands to reset firmware, but the same thing happens. I have tried pressing the CUDA button and also removing the battery for a few minutes, and it doesn't work.

Could the NVRAM be corrupted? Can it be replaced or does it include the boot ROM as well?

I have OS9.2.2 on the first partition and OS8.6 and I can't boot from OS8 because it doesn't save the selection in the boot menu and the ALT key doesn't work when starting up.

 

[aladds]

Which commands are you typing into OF for a reset? “reset-all” is actually a reboot.

Have you tried Command-Option-P-R and waiting for 2-3 chimes?

Also I note you say “ALT” not option. Are you using a PC keyboard? Sometimes the window and Alt keys are swapped.

 

[indibil]

I use the Apple and Alt keys, together in the photo, original Apple keyboard, Alt=Option.

Command-Option-P-R, I've made three chimes and it's still the same.

Three commands are used in Open Firmware:

reset-nvram
set-defaults
reset-all

Same error.