Powerbook G4 1.67Ghz Chimes but won't turn on

We have a Powerbook G4 1.67Ghz. When I tried to wake it up the screen remained black. When I try turning it on and off it will chime but the black screen remains. I noticed that the lights on the keyboard and the Apple light on the back of the screen don't turn on either. The battery has been working fine. I tried taking out the battery, etc...someone tried to hook it up to an external monitor and still did not work. She said she has to send it in and thinks it is the logic board. Does anyone have any ideas if that is correct or what else the problem could be. It seems too expensive to send it in for a logic board, it's not even worth that much.
thanks.