Call Pop A Lock or go by a locksmith or body shop and let them slim jim the lock open. I will bet it is simply jammed - suprised using the key and pulling on the latch / button will not open - how about key and pulling on the inside opener loop? The inside latch can be removed with the door shut but I agree the panel cannot be removed w/o damage with the door closed.
Hope you are not going to tell us later that it has been in an accident recently or that an alarm has been added....