No radio sound after battery replacement
 

Replaced the battery in my 2001 E55 AMG and expected to get the word CODE on the radio screen but instead got a blank screen. Talked with dealer who advised that there is a fuse at the rear of the radio. Pulled radio, replaced fuse and "code" appeared but when code was entered screen came up normally, but no sound. Any ideas?

Did the battery cables get reversed? Seems odd that the fuse blew.

This sound system has an amplifier that also has its own fuse. Replaced it and now I have sound.

First things first always check fuses first