same thing happened to me... it sucks...

Anyways,my friend (former BMW master tech) un-did the door panel and it took him a while to get the door open...
Once he got it opened, the door opened and closed fine... i'm glad it was not an actuator because those list for $199.99
we did lube up the door lock afterwards... its F*cking stupid... I dont know why a BMW door would get stuck.