I'm embarrassed to say but my X3 155000 km, failed to start after an automatic engine stop (start/stop) for few hours.
I have been into a high mountain area, no cell signal, no spare Key.
Finally starts, drove straight home, checked with Autocom CARS CDP+ | 2013 Release 3 (2.13.3) and having a bunch of codes.
If helpful please see the attachment with those codes.
Since then the car is behaving normal by all means.
Some of them are from battery disconnection in an effort to reset de car software.
I'm afraid to go for a BMW dealership I had very bad experience with them.
Some advice will be greatly appreciated.