MAC - Stop Struggling With The Power Button
Some late model PowerMac G4s are notorious for being difficult to power down manually. For example, if your system freezes and you need to press the power button, you may find that the system doesn't respond to your action, in spite of holding down the power button for several seconds. The solution to this problem is to apply pressure to the northwest quadrant of the power button. The actuator switch is located behind this area rather than behind the physical center of the power button.