Can't change the station and there is no sound.

My alpine car radio does not change stations, neither manual or seek. I can change the digital display (volume, bass, treble, balance, superwoofer and fade) but not the stations and there is no sound with the exception of a slight hiss. I recently had a fan replacement requiring the removal of the battery but the repairman said that the radio was not touched. When I got my van back that’s when the problem surfaced.