Sounds like the drive has either crashed or you have updated the firmware.

There is a procedure for bypassing the code problem, is in the back of the nav manual.

Here you go

Emergency deactivation

1. Disconnect the battery and wait about 5 minutes before reconnecting it; refer to Owner's Manual for Vehicle

2. Turn the ignition key to position 1.
A ten-minute countdown appears on the screen.
After the ten minutes have elapsed, you can start the engine.

After this all will be as normal.

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Sept 03, M3, Silver Grey. Retro-fits: Modded Mk4 DVD Drive, OEM Bluetooth, VR Control, Rainbow Speaker Upgrade, Sony SOT Amp, HK Sub, CCFL, Intravee II, NightMode.