i have a bmw 528i year 2000.that didnt start after the alarm went off?

the alarm of my car went off this morning while it was parked on the street (dont know the reason), and then when i tried to unlock it, it didnt unlock, after a little help from a friend i was able to unlock the door, but now the car has no power at all, the dealer said that it might be double locked. can some one help me with this issue.