iMac G3 won't reboot

[Nermal]

My iMac G3/333 has developed an interesting issue. It boots fine, and it shuts down fine. But it won't reboot! When I try to reboot, the OS (tested 8.6 and 9.2) shuts down, the screen goes blank, the power button turns orange, the CD drive makes its 'reset' sound, the fans continue to run... and it just sits there.

If I press the power button at this point then the fans stop and the button remains orange. Pressing it a second time causes the system to boot successfully.

I've tried to reset PRAM but Cmd-Opt-P-R is unsuccessful. It chimes once, the power button goes green for a moment then back to orange, and then it gets stuck again. If I use Cmd-Opt-O-F then I can do reset-nvram and set-defaults successfully, but reset-all results in the same issue.

The PRAM battery is only about a year old.

Any ideas?

 

[TheShortTimer]

Have you tried removing the RAM and also pressing the CUDA button on the logic board? That worked for me when my iMac G3/333 was playing up and would boot to a black screen. Worth a try.

 

[Nermal]

I'd actually forgotten about the existence of the CUDA button. I'll give that a go in the morning. Hopefully I don't need to reseat the RAM in the bottom slot since it's such a pain to get to!

 

[Nermal]

CUDA reset fixed it. Thanks!

 

[TheShortTimer]

CUDA reset fixed it. Thanks!

Excellent news! You're welcome.