This is Weird, it has happened to me again but my issue is different than yours i think.. I've seen most of you on google search and you tube have had the lights come on in the car where as my car is different.
in the last month it has turned off about 5 or 6 times, where the alarm sometimes will come on and all lights and engine will go off and nothing will come on you put key in out in and out same thing but if i leave it for a day or so it comes back on until recently it decided on Saturday to stop on me and not come back on but it has been very cold since then.
I bought a new battery and paid £185 quid and the mechanic came replaced battery and no joy same thing and he tested my old battery and said its fine.
So im returning the new battery back, but was wondering has anyone figured out what could be the cause or how to resolve???