My driver window failed like that. It went up most of the way, so I tried to put it down and up, but went even further down. Drove it to the dealer and they said the drive belt inside had worn out. I am still suspicious of that because I had them replace a broken door handle on the same door a few months earlier. Always wondered if they did not put the belt back on track properly. I only took it to the dealer because it looked like a nightmare to take apart with all the wires to control the locks, mirrors, etc. Figured if they screwed it up I could get it fixed again for free.
If they make a Chiltons, Clymer, Hanes, etc. manual for the car you can see what is involved in disassembly. Having replaced the connecting rods for the locks in my older cars I can say that there is not much room to maneuver inside that space. Hopefully no special tools are needed, either.