I just replaced the PCB on a drive I have with another one of the same model but the FW/PN were different because I couldn't find the exact match. I don't really care about the information on the drive this is more a learning experiment, but when i put the new PCB and plug the drive in I'm getting no power to the drive. The light turns on, but nothing happens, the disks don't spin and the head doesn't move.
The old PCB still powers up the drive but the head keeps ticking out of control, I see it just moving back and forth. So basically the old PCB powers the drive but I can't access it because the head won't relax, and the new PCB doesn't seem to do anything to the drive. Any idea whats going on here? How do I test the new PCB to see if its working?