have a 84 380sl with a Becker Gran Prix radio. Today I was driving around and it was working without a problem. I stopped for 5 minutes at a store, came out, started the car and the radio doesn't work. Instead of music I get a loud thumping noise from the speakers and the radio has no characters radio station display . I can't turn the radio off ( to get rid of that thumping noise). In addition, the power antenna won't go up. I tried pulling and replacing the fuse but that didn't solve the problem. Any idea what the problem is?