I'd be pretty careful how you push and pry. You can damage the door. If the car in your avatar is what your working on and it's a vert. I believe the doors are vert specific. Passenger door on my sons 69 was stuck. Same thing. Push the button pull on the door etc. I did what you did. AeroKroil, PBS blaster etc got hands in there and worked the **** out of everything. After about 2 weeks it finally opened. Car is in the shop now for its restoration. I plan on pulling those latches, and soaking and degreasing them. Then relubing them with Aeroshell 7 synthetic grease. The striker plates on the door jambs have a tendency to crack.
If you just cannot get it free, You may want to concider cutting loose the latch pin from inside the quarter panel, then remove the door hinges to get the door off. Then you can remove the latch from the door and free it up on the workbench. Dynamic renovations makes nice striker plate repair kits for this spot.
