I have a 500 Mhz, 256M RAM,G3 Pismo that recently stopped booting. It would only spin up the HD and never complete the HW test. Recharges batteries, shows Caps Lock light , spins a CD if inserted , gives an Ethernet link light , spins up /down a FW connected HD , etc. I have removed all components to the bare shell and rebuilt it to reseat everything. I found two burnt components on the logic board underneath and slightly toward the back from where the PRAM battery plugs in. There was indication of arcing or lots of heat on the shell underneath these components. Ordered a replacement logic board from PowerBookMedic and installed that. Upon pushing the power button with new logic board , same symptoms. HD spins up and nothing further. Any tips or suggestions ? Would it help to know which components got fried ? I could probably locate the circuit board numbers etched around the components.
Order #43827.

If the logic board still doesn't fix the issue, you are likely looking at a processor issue.

-Bradley
Powerbook Medic