To access the Service Menu :
1) Push and hold the iDrive controller up for about 15 seconds
2) Turn controller 3 clicks clockwise
3) Turn controller 3 clicks anti clockwise
4) Turn controller 1 click clockwise
5) Turn controller 1 click anti clockwise
6) Turn controller one click clockwise
7) Depress controller
Service menu will appear in the settings menu, right at the bottom.