Chosen Solution
I got a iMac G5 iSight 20 inch from a vintage computer store for 25 dollars, bringing it home, I put in a hard drive and new ram of 2 gigabytes, and the hard drive came with Mac OS X Leopard, I got the hard drive from the same place for 8 dollars. I powered it on and no sound, nothing on the screen, and the LED light was flashing in a loop, and you could not power it off, and the fans did not even run.
You’ll need to check the power supplies capacitors, review this Capacitor Plague. If your caps leaking or blistered time for a new supply or fixing yours