Originally Posted by compress ignite

Enter it and see.
If you don't have the code,any MB dealer can access it from the VIN.
Second thing would be the Miro-fuse in the back side of the radio...
As they get older sometimes they get "Sensitive"
(And the voltage surge from reconnection may have Boogered it[the fuse]. )

Nutcase that I am, I Always pull the Radio fuse(s) in the Fuse Box before
dis/re connecting the main power source.

Last (and hopefully not necessary) Resort, Becker NA can fix no matter what.