Why does my PowerBook freeze up on start up

Having a problem with my g3 powerbook freezing up when i turn it on,It sometimes gets to the apple,with the circle spinning then freezes,or to the main screen page then freezes up.Then the power button won't turn it off.And if unplugged it won't turn on again,and reset button does'nt help.It just makes a noise when pushed,like it's going to start but nothing happens.Have a new power cord,battery is tired,but shows it's charging.When comes on and freezes the CD drive is able to open,and i put a cd in but nothing works.That's all i can think of right now.Thanks in advance.Solomon