A dead battery can be caused by a faulty seat control module that does not properly shut down. Spilling liquids on the front seats can cause these modules to fail.Google+
Car Problem Reports
Mercedes-Benz C350 Dead Battery Due to Failed Seat Control Module
Mercedes-Benz C350 Problem
Visitor, 2008 Mercedes-Benz C350, 60,000 mi
My battery died about 3 months ago Nov.2013 and I got a new battery, later to find out that my passager seat electronic adjustment no longer moves forward/backward evenly. The plastic bracket used for electronic connectors is broken on both ends in front of the seat. The seat moves up, down, incline, and declines ok but does not move forward/ backwards evenly. The right side of the seat seems to be moving forward, while the left side is stuck. Forcing the motor gives it a burning smell. HELP!!!!