Also having similar problem
Shut off car for 30 minutes. Return to dead car.
Doors are locked, and won't open with key, or with Fob, or with BMW assist.
Climbed in trough trunk, and the can't get doors open from the inside either. The start button does nothing, no interior lights.
Car has a new battery, and the battery voltage is measuring fine, so it isn't a dead battery. New battery was a result of a more minor problem a fw weeks ago
I'm perplexed. What if I was inside the car - I would not be able to get out! This seems to be a serious safety problem with the design of this car.
I will search more about the IBS. This may be a clue. Car is under extended warranty, and will be towed to the dealer. I want to understand better, so I can decide whether to get rid of the car.