[Macola]

I was given a dysfunctional MDD G4 PowerMac recently...this is the dual 1.42 FW800 model. The battery voltage was low, so I replaced the battery. It started up fine, but on the next attempt, it refused to start when I pressed the power button. I tried (sequentially) resetting the PMU, PRAM, NVRAM, removing the battery, unplugging from AC. The only way I can get it to start up reliably is to unplug it for a minute, after which it powers on just fine.

I don't know if it's worth the trouble of a Genius Bar diagnosis, but will consider any ideas. Thanks.

[Mister Elf]

I had a similar problem with my blue and white G3 back in the day. It's a power supply problem; you need a replacement. Should run you around $50-$80 if you find a good source.