Hi! I'm new to your site, but I find it quite helpful. I dismantled my PowerBook G4 15" because after it was knocked off a desk by a so-called friend, the lower third of the screen is not displaying an image, but lit (not dark). If I put pushed on the bottom left corner and pulled on the upper right corner, everything rights (see video). It used to stay that way once I applied the pressure, now it won't. I took it apart down to removing the border of the screen and checking all the connections, but to no avail. Everything seems to connected ok. Check out the video and let me know what you think. Thanks!

http://www.youtube.com/watch?v=pDWpr-9R3tQ

the 1/3 issue is a common LCD problem. You'll need to replace the LCD in most cases.