Difficulty Starting Up

Hello,
My PowerBook G4 1.25 is becoming increasingly difficult to start. Merely hitting the power button is not working. I have to hold down the button for a few seconds and hope for the best. The last episode it took an hour of trying before it would turn from a black screen to a blue screen. When holding down the button I hear 1 to 3 clicks then nothing. Sometimes when holding down the button I hear the clicks then a screeching sound. I have been leaving the computer on sleep instead of turning it off but with this last episode I wasn't paying attention to the battery.
OS 10.4.11
1.25 GHz PowerPC G4
512MB DDR SDRAM

Thank You for your help.