It's usually a completely flat PRAM battery that is to blame. Do this: Push down on the two tabs at the top of the keyboard and flip it over and down down onto the palm rest. Now you will see the banjo shaped PRAM battery on the lower right just below the hard drive. Pull the white PRAM battery connector out of its connector and put the keyboard back. Connect the power unit, turn it on at the wall and press the power button. 9 times out of 10 the Powerbook will start up and begin to charge.