Won't Reboot After Startup

I recently purchased an iMac G3 (Blueberry) just because!

It booted up the first time! But, it won’t restart or, if shutdown, won’t boot again.

If it sits for a couple of days, it will boot up properly, but still not restart or shutdown and boot again. The power button on the console glows amber (not green) and I can hear the disk spinning but no joy.

I zapped the PRAM but no help. I removed the logic module and reset the Cuda button and still no change. I put in a new PRAM battery - still not working properly.

I think the next step is to reset the Logic Board.

Anyone know why it would reboot if sitting for a couple of days?

Any other advice?

Thanks,

Greg