See also:

Activating HDC
Press the button; the LED above the button lights up. ...

Priority options
The driver has priority The source selected via iDrive in the front is output on the vehicle loudspeakers and can be selected but not operated from the rear. Other audio or video sources ...

Initialization after a power failure
After a power failure, it is only possible to raise the roof, if necessary. Have the system initialized by your service center. ...