A friend has a G4 Sawtooth that has performed flawlessly until recently. Now it occasionally refuses to start, with no light on the power or monitor button, no fan noise; and in all respects it acts like there's no power. Most of the time it does start right up. Once or twice it has started and run for a while, then it goes out, and later comes back on by itself.
He took it to the local certified Apple shop, but they were unable to get the computer to reveal it's comatose side, despite leaving it on for several days
If it powers up, then it will usually run fine, with no apparent software problems. Does anyone have any suggestions for diagnosing this problem? The Apple tech apparently could not find a problem when the computer was running. Is there some way to isolate the problem when the computer is in its comatose mode? Could a loose connection be the culprit? Is it worthwhile to replace suspected parts until the problem is resolved? What parts are the most likely suspects?