Its best to use a proper scan tool like Star or at least carsoft to see whats up with that situation you have. The transmission control unit "talks" to the gearshifter unit to verify what gear position is selected. This system is also part of the safety start system (start in P and N only) - if it goes TU you need a shifter console (but this usually goes bad if it went on a drinking binge from your beverage spilling from the cup holder)

The transmission only has 4 mechanical movements from the shifter P R N D the lower functions dont move the rod at all, those 4 individual select gears are all done electronically as the shifter sends the command to the transmission control unit.

If you can somehow get the car to start and manually move the shift lever on the transmission (you will set an error code this way) and the car starts to move the mechanical function is OK - your problem is in the shift box. On the older cars (96) this problem is usually because of the cable interlock pawl breaking and locking the shift lever. Yours may or may not have this issue.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)