I have a OBS,iMac G5 (17-inch) that won't start. What is possibly wrong?
My computer won't start.
If it does not power on at all, the cause may be as simple as a corrupted parameter in your iMac's System Management Unit (SMU).
Try resetting it according to the following instructions:
If that does not prove successful, carefully read and follow these instructions, which include the above procedure:
iMac G5: Troubleshooting when your computer won't turn on
Good luck, I hope you can get it working again!