A limited number of Power Mac G4 (Ethernet Gigabit) computers do not turn on when you press their power button.
Solution
1. Make sure that the power cord is firmly plugged into the computer and the wall socket.
2. Try another wall socket to make sure power is getting to the computer.
3. Open the computer's door and make sure the ribbon cable to the front panel board is connected securely. The front panel board is located behind the power button. (See Figure 1.)
Figure 1 Front panel board cable
4. Also, make sure the front panel board ribbon cable is connected securely to the logic board. (See Figure 2.)
Figure 2 Front panel board ribbon cable
5. If the computer does not turn on after following steps 1 through 4, contact an Apple Authorized Service Provider.