[TonyS]

Walked out to the car this morning and it's sitting there unlocked (luckily in the garage) and completely dead. Nothing works at all. I thought it might be the battery in the key fob initially (wishful thinking) but the spare key is the same.

My immediate reaction was "flat battery" but I'm pretty sure I locked it all up properly, and I thought there was circuitry in there to stop the battery draining too far anyway. I do know there's a "battery disconnect" switch that triggers if you have a serious crash - I wonder if that's gone off?

Just called BMW Emergency Services to come and sort it out - luckily I wasn't going anywhere too important. Also lucky that it died here at home and not yesterday when we were out miles from anywhere.

I'll give an update when I know what it is.