Hello friends! I have just purchased an SL350 and have a few little issues with it so im sure you'll see my name popping up a bit! I have a problem with my comand unit on my SL350, my previous job role was electrical engineer so im quite handy and understand most things relating to this. when i press the on button for the comand unit the back light comes on and i can hear the disc spin - No sounds can be heard and no graphics at all are shown on the display - not even the mercedes logo. It will allow me to eject the nav disc in the unit but that is all. I have a bose system with cd changer in the storage compartment behind the passenger seat. I have removed the unit and checked the 10amp fuse which is ok. I have also done the fuse reset by removing the fuses behind the drivers seat storage compartment for 5 mins and reinserting them. When i have all leads in the back of the unit except the fibre optic i cannot see a red light (send signal) coming out of the unit. The only thing i know is that the secondary battery went flat and was replaced and now comand not working. I also know the comand unit was replaced back in 2007 under warranty. Please can anyone help?