Probably a fuse problem as that was what happened to me. The fuses are made of a lead and mate to a brass connection. The lead oxidizes and opens the circuit. You don't have to replace the fuse, just clean off the oxidation from the lead by scraping with a knife. For a more reliable electrical system, clean all the fuses. You should also clean the brass fuse holders when the fuses are removed.

This appears to me as a quality problem with MB. American plug in or bullet type fuses do not have this problem. Wake up MB.

P E H