I have an 88 M3. I recently had some work done on my car which involved disconnecting the battery.When I got the car back the code indicator was displayed on the radio. I entered the code and nothing happened. I tried it several(many) more times and the only thing that happens is a beeping noise during entering the code. I have turned the car on and off and still no luck. Its been several days and I have repeatedly tried with no progress. I no its not the code because i have used it before. Please help me i think im going to go crazy!!!!!!!!!!!!!!!!!!!!!!