I had an 1989 Ford Ranger, shared some of the same sheet metal with a few of the Explorers in that era. Anyway, I had a similiar thing happen on mine. I was able to open the door with the inside handle, although with considerable more effort than normal. I went ahead and forced it open. Did not hurt anything on mine. The electric actuator had siezed on mine. On mine the actuator spins a threaded rod up and down to work the lock pawl in the latch mechanism. The actuator has a rubber boot or balloon covering it that had come apart and let water and dirt into the motor.

If you can figure out which of the little levers on the latch is the lock pawl you can push or pull it to unlock the door. A locksmith uses a couple of wedges between the outside glass and weatherstripping at the base or belt of the door to get some room to work in. Slips a pen light down into the door to see and then takes his little tool and flicks the lock pawl. I have done this a couple times on my Honda. You get pretty good at it when nobody else is home with the other set of car keys and you just locked the keys in the car on Sat. night.

I used a couple of 1" putty knives as wedges, slip the blade between the glass and weatherstripping and push in until the handle is against the glass and the blade is pushing the weatherstripping out. Do this a few inches apart and work in the middle. Shine your flash light down into the door so you can see the latch mechanism. Being dark outside helps with the background light so you can see into the door easier. I bent up a coat hanger to push or pull the lock lever on the Honda. I cant remember which way it went, up or down, that was a couple years ago. If your carefull I don't think you will hurt anything, especially if you can see what you are doing. It will be a tight fit to see in there, rolling down the window might help to see in there too.

If his problem is the actuator, look on the net to compare prices if you buy a new one, my prices ranged from 35 to 55 for the actuator.

After thought here, follow the rod from the outside lock in the door down to the latch to see where the lock lever is.

good luck

Gary