Reset parameter random-access memory (PRAM). Hold down Command-Option-P-R during startup until you hear the startup sound twice.

The system software could be damaged. Start up from the system CD that came with the computer.

Remove the user access door.

Touch a metal surface inside the computer.

Disconnect the AC power cord. Press the PMU reset button on the logic board. Refer to “Resetting the PMU on the Logic Board,” earlier in this lesson.

Check for external video. Connect an external monitor to the video out port and start up the system again. Did you get external video?

Yes: Replace the display/analog assembly.

No: Replace the main logic board.