[SLx3]

Hi there, woke this morning to my 2013 X3 alarm going off periodically. Went to investigate, car couldn't be opened electronically (tried both keys), opened manually and the car is completely dead - I couldn't get the alarm to stop although it has since stopped on its own. The hand brake light was on, now even it isn't lit up.

Was running fine last night, I didn't leave anything on that I am aware of.

There is a noise coming from the dash air vents, sort of sounds as though the air is on (faint but noticeable), otherwise it's completely dead.

I am waiting for my father-in-law to get back to me to see if he can try jumping it, but in the meantime, I thought I would see if you guys have any ideas to what the cause could be, does this sound like just a dead battery? Its the air type noise that odd to me (though I don't know a thing about cars lol)