I'm surprised by the MB element here. Very disappointing.
As far as blackmercedes comments, he is right on target. It has never ceased to amaze me that someone would put their car in the hands of some high school kid who doesn't even understand, or has never even heard of "Ohms Law" and let them start cutting and splicing into a wiring harness. I've seen cars with nails driven in the battery post with unfused feeds running off to who knows where. I don't understand why you don't see a car burning on the freeway every day.
Have a great day,