Hi, Peter, and welcome to the club! No, there are no active/passive or on/off switches on a stock Alembic. Also, you bass should put out little, if any, sound without a battery that is at least partially charged. The first thing you might want to do is test the old battery and see if it has juice. If it does, after ten years, you might want to contact the Guiness World Records people! Otherwise, put in a fresh battery and see if that changes anything. If your original battery is dead, and a new battery doesn’t change anything, I would strongly suspect that someone has messed with the electronics. In that case, you might want to take a picture of the control cavity and post it so we can help you diagnose the issue.
Bill, the guitar one