MacBook Air black screen workaround

Failure phenomena:
1. Sound on Boot
2. Rear Logo Light
3. Keyboard backlight does not light
4. Caps LOCK key is not lit
5. Screen black screen, no Apple logo

FIX: After resetting the pram, the boot is successful.

1. Turn off your Mac.
2. Locate the following keys on the keyboard: Command (?), Option, P, and R. You need to hold down these keys at the same time in step 4.
3. Start the computer.
4. Press and hold the Command-option-p-r key before the gray screen (press the Power key to press the four keys immediately)
5. Press these keys until the computer restarts, and you will hear the startup sound again (you can release the button when you hear the startup sound)

Transferred from: http://bbs.feng.com/forum.php?mod=viewthread&tid=8801764&extra=page%3D&page=1

MacBook Air black screen workaround