You say that the battery has been removed, but what about damage to the M/B? Have you got memory on the maindboard in addition to chip ram? If so remove it and reboot.
Have a look at the caps at the back of the board, at the ports - the audio caps tend to leak and can seriously damage your board. Have a look round there for signs of corrosion.
If you thibk the board needs repairing, Amiga Centre France can do board repairs and are alot closer than Anthony Hoffman. Amikit in the UK have just started up a repair service, might be worth a look. I haven't heard any reports about them. Amiga Centre France has a good rep and gets good feedback.
