See also:

Switching off
Press the button repeatedly until the LEDs go out. ...

If the worst comes to the worst: BMW Assist Emergency Call with automatic vehicle location
In the event of an accident in the new BMW 3-Series, the Advanced eCall function from BMW ConnectedDrive allows the emergency services to receive detailed information on the type of collision and ...

Sound output
Switching on/off When the ignition is switched off: press ON/OFF button on the radio. Muting When the ignition is switched on or the engine is running: press the ON/OFF button on the radio. ...