Are you using 10.5.x or SL? I run 10.5.8, and mine had the exact same symptoms; blank backlit screen, no picture. There's two ways of fixing it- replacing the AppleIntelGMAX3100FB.kext and adding Natit.kext (both available from links in my sig), or patching the DSDT and adding display overrides if needed. You may be able to boot using -x, then turn on Screen Sharing so you can work on it using a different pc.
I got it working on 10.6.2, but only in safe mode, otherwise all I got is a blue screen.
Damn. how can I get rid of "-x"? Is this a know issue or what?
Your AppleIntelGMAX3100FB.kext and adding Natit.kext can get me free of "-x"?
See my previous post:
OK， great news:
I finally got native screen on thinkpad T400 with x4500 in snow leopard, 1440x900@60Hz,
However, only in safe boot mode. Otherwise, it gives a damn blue screen as I said earlier.
I couldn't capture screen at this moment, can only get a blank white one. Dunno why.