Audio Systems: 02 ML320 Stereo Problem, stereo head unit, fiberoptic system

Question
Hi Ernesto. I have a problem with the MCO unit (stereo head unit) in the car above. There's no output to the speakers and it does not recognize the installed CD changer in the rear of the vehicle. The battery did die, and the code was entered correctly following this. Any ideas?

Answer
the audio system in your vehicle is a fiberoptic system and it is a LOOP  if the loop is open there will be no audio
it looks like the cd changer is bad and the light is not in the circle loop anymore you need to remove the cd changer or have it repair if you follow the cable couple of inches ( orange cable ) you will find small metal clips take that apart and close the loop  there will be light coing to the amplifier and you will hear the radio again
good luck