BMW Questions? Ask a BMW Repair Expert for Answers.
On your vehicle there is a fiber optic bus for all of your entertainment system, If this bus goes down you will have all of symptoms you are complaining about. Warning lights on and no sound. There could be several reasons for this a failed control unit to a broken wire. It will take a BMW diagnostic tool to determine what module or wire has failed. My best guess is the amplifier module is the cause they are a common failure on your 750i as for replacement it will need to be done at the dealer because it needs to be programmed to your vehicle for it to work.