Macbook Air White Screen Issue

Hi,

So here's my dilemma. I got a used macbook Air for Christmas. It's a 1st gen 1.6 ghz 120gb hd (not ssd) 2GB ram and definitely out of warranty.

The thing is, the computer boots up completely, but the Screen just stays white. I know the computer is booted because it works fine in an external monitor. Any idea what might be wrong?

A little bit more info, my brother said the guy he purchased it from replaced the screen, but then the white screen came back. He thought it might have been a cable somewhere or the logic board...the thing is, if the computer works fine in an external monitor, could the logic board still be damaged?

More info, it actually is a 1.1 Macbook Air, I just checked out the specs from an external monitor. Its a 80gb HD, my apologies. I'm also posting this from an external monitor running the air right now. Any suggestions to try?