Macintosh Powerbook G4 will not boot up!?

I have a question for Mac Computer experts. I own a 2006 Macintosh Powerbook G4 that will not boot. I've tried swapping batteries, swapping AC adapters. I'm out of ideas. I'm thinking it is a power supply failure. Everything, the lights, Screen, or fan will not work. The computer has no water damage, nor has it been dropped. I'm desprate. Anybody who has ideas, I would apreciate them. I'm on a tight budget, so I cannot buy another computer until next year. Any ideas would be appreciated! Thank you for your time.