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!