I just finished getting my drivers door on my delta88 working again (it wouldn't unlock)
basically I had to take apart and remove the door panel while the door was closed...reach in and manualy open the door (tecnically the door was still locked)
in my situation it was a rusty spring in the rod from the outside handle/button to the door latch/lock mech. WD40 and some figiting later the spring was rust free and the door works better then the other 3 now
I was very lucky that the spring isn't damaged it was just gummed up and coated in dirt and some rust.
my door handle button felt the same as alot of ppl complain of ... after trying to unlock the door their is no resistance to the button and the door doesn't open nor does it unlock
BTW while on the topic of inner door fixing... Cheap door panel remover for all of you... get a normal 4 prong fork... bend 1 of the 2 middle prongs completely back... VOILA! you have a tool to remove the panel with the little plastic plugs without yanking them out of the cardboard backing and ruining their mounting spots in the panel