I have a Sony Vaio FX501 which had a bad disk. I opened it up and fixed the disk, but when reassembled the on/off switch has absolutely no effect. I did forget to remove the battery initially; could I have shorted something ? I have checked all connectors and wires and nothing is loose. I have reseated the obvious ribon cables. The same lack of responce is apparent whether connected to the mains adapter or just battery only.