The symptom you are describing is common when any of the components of the audio system malfunction - when the COMAND attempts to start up, it attempts to establish communications with the other devices on the fiber optic ring. If it gets no response, it will cause it to hang.My 2006 CLK350 has the Navigation DVD and audio CD players. The Navigation DVD player stopped taking the CD last month so I disconnected the battery for 60 minutes and powered the unit back up. Now I only get the Mercedes Benz logo on the screen and it stays on as long at the unit is powered. Nothing else. Nothing will function now. Is there any way to get the COMAND unit to go back to normal? I want to keep the original unit. Also I wondered how I should disable this COMAND unit and still drive the car if I have to.
The problem could be any of the audio components or telematics devices - these include the CD Changer, SiriusXM tuner, cellular phone transceiver, and Tele Aid module. Any of those devices malfunctioning could cause what you are seeing.