I have the same problem. Huge PITA. Please post if you have success or know of another thread.
I kept working at it until I got the piece of cable to engage the latch and pop it open. I used a small pair of vice grips to pull the cable.
I talked to another body shop that said to grind those three round things that look like rivets. They said the metal plate should come off, and the latch can be pried apart until the only thing left is the inner latch that holds the door closed. The is just a matter of rolling the latch off the door pin.
Here is the parts I am using to make repairs, links below. My latch is still good and very easy to open after I cleared out the broken cable pieces. I'm doing all of my doors and replacing the furls (12 total) on the ends of the cables to prevent it from happening again. I'm also using dry lube inside the cables to keep them lubricated.
Here's a tip. If the door has an inner and outer handle, it takes two cables. The cables are different between the side doors and the rear cargo doors. If your van has barn doors on the side and the back, that's six cables that can break or jam up.
Amazon doesn't have the latch, but most parts stores can get it. It should come with cables and the rods. These parts should fit 1992-present.
DORMAN 940690
Cable End Furls
Rear Right Door Cables