I have a 15 inch powerbook G4. I cracked the screen so I replaced it. I replaced the entire top LCD portion. When I removed the lower half of the keyboard, I needed to reconnect the wires and when I put it back together, my powerbook would not turn back on. I don't know what the wire is called that goes from the bottom of the keyboard that connects to the main part of the computer, but when I manually start the computer it turns on but none of the keyboard functions work.