Backlight stops working, but only after boot.

[r3dplanet]

Hi there.

I'm working on a unibody Macbook model A1278 that had a liquid spill. I've disassembled the machine and cleaned it thoroughly with alcohol and compressed air.

When I start the machine, I get the normal gray screen with the Apple logo. As soon as it brings me to the desktop the backlight stops working.

Strangely, when I install a new OSX installation on a separate external USB hard drive, the entire procedure works just fine. The screen is clear as can be. Once it reboots ... *poof* ... and the LED "backlight" just turns off.

I've already reset the PRAM.

Any ideas?

Thanks!

 

[yadmonkey]

The first thing I'd try is to reset the power manager:

http://support.apple.com/kb/HT3964?viewlocale=en_US&locale=en_US

 

[CausticPuppy]

My MBP was doing that for a while.


This will sound stupid, but try it: when the screen goes dark, try using the brightness control to turn up the brightness.
When the brightness is turned all the way down, the backlight goes off; so mine was resetting to minimum brightness every time it booted up (or woke from sleep).