Passenger window will not go back up

The fact the window works in one direction proves the wiring between the door hinges is okay. That leaves the switches, but it is important to understand either switch can cause this. Both switches for the passenger window have four sets of contacts. When a switch is activated, two of those contacts remain unaffected, (released), and the other two contacts turn on, (activated). Two sets of contacts in the other switch are still in the circuit and must be good for the window to work. This also applies when a window works properly both ways from one switch but only one way from the other switch. It can still be either switch that is at fault.

Normally I do not approve of throwing random parts at a problem to try to diagnose it, but in this case, and given the age of the vehicle, I would suggest finding a pair of switches at a salvage yard. Try the passenger switch first as a test. If that does not solve the problem, try the driver's switch assembly. Keep in mind one of those could be bad too. The previous owner would not repair a window problem if they knew the vehicle was headed for the salvage yard soon.

We can also figure out which switch is bad with a series of voltage measurements at both switch connectors, but given the time involved, it is much faster in this case to just pop in another switch as a test. If you cannot find replacement switches, have a test light ready, and a helper if possible. A digital voltmeter will work too, but for this type of problem, a test light will be more accurate. I will find a wiring diagram and figure out which wires to check.

Removing the switches is easy, it only takes a thin tool to reach under the rear edge of the switch trim plate to release the clip and the switch comes out of the door panel.
The switches can be removed from the trim plate, it is a common GM switch, used in many vehicles.

I would switch the drivers side first as the most likely item to cause this fault would be a bad ground contact on the down switch in the drivers door. It is the common point for both doors on the up side of the circuit.

To test it you could pull the drivers side switch and put a jumper wire between the tan wire and the black wire (ground). Then try >> only the up switches.

Have you had any success or no time to look at it yet?

Please let us know.

Cheers, Ken

Door lock stuck or is it the latch?

I thought you had a bad window control? The rear hatch should not have anything to do with that.
However, you should be able to remove the hatch inner trim panel or if this was one of the later build date vans there may be a box outline in the rear panel over the latch, that is an emergency access panel.