I had to get a little rough with it. just remember that you only need to pull on the handle enough to move the plastic.

put your full force of opening the door in your OTHER hand that is on the door itself.

 

how do i remove the door panel without breaking everything? The latch is not rusted. For all i know the door itself is jammed due to an accident.

 

I'm working on the same problem.
The control rod for the lower latch had come out of the handle due to the lower latch being rusted and immobile.
Unfortunately, the lower latch is so corroded the metal just bends when I try to operate it with pliars inside the door.
I wish I knew how the lower latch mechanism worked so I could possibly figure out another way to open it and get it on the workbench to refurbish it.