The car began to have a dead battery after it sat over the weekend. Jumping it on Mondays and driving it back and forth from work it would start every day. Come the weekends it got the no starts again. I have a friend that is a mechanic for a living. He looked in his service literature and the first fault listed was the sound system. By checking the current drain on the battery while parked it was showing nearly 2 amps and would drop to 1 and a half. Pulling the fuse number 42 would clear the drain. I looked online at a youtube video and the fellow showed how to install a relay that would open the offending wire when the ignition switch was in the off position. In closing, many years ago German products were among the best made on earth but this vehicle has been the pits from the onset.