So, if we walk through the attraction:
Station 1: Ready room with BB-8 and Rey and outside the shuttle.
I don't see anything here that is any more complicated than the Collector's office in GOTG. So I'm going to say everything here is fairly reliable.
Station 2: The shuttle on a turntable
It's a big turntable, right? One or two identical shuttles? A couple of really cool animatronics and a whole lot of screens. I'm guessing screens are pretty reliable. If there are two shuttles, then that gives redundancy - But I suppose if the Lt. Bek animatronic goes down that shuttle goes down. But the other shuttle can continue and I have to imagine techs can work on one shuttle while the other operates, so it seems this might slow loading, but not likely stop it unless the turntable itself has an issue. I haven't been on it so I don't know how intense the motion simulation part of this is, but I imagine it is pretty tame since you stand the whole time, right? So this seems unlikely to be the "show-stopper" And when it is...in WDW they just walk you past it...(not cool...not cool).
Station 3: The star destroyer
Animatronic Storm Troopers, most of which if they were down you wouldn't notice, right? Minor movement. And cast members. So...
Station 4: Interrogation room
Again, nothing more complicated than the Collector's office, except maybe the break-out effects. mostly projections, which are high reliability...
Station 5: The show proper
So it seems that this is where we see our issues likely. We've got trackless vehicles that need to constantly be recharged, right? The vehicles go both indoors and outdoors, so can pick up dirt and bring it inside. The Kylo Animatronics both seem to have a "B" mode to cover for when they go down, so those don't seem to be showstoppers. Not sure about the Finn animatronic. We've got lifts at the AT-ATs which I assume the ride vehicles lock into during ascent. We've got the light saber effect which some folks have reported going missing, so that doesn't seem to take it down. The gun room needs to be synchronized to let the vehicles past, so there is a potential failure point. And then there is the drop rooms that the ride vehicles lock into. Are there two or four of these?
Station 6: Back on Batuu and unload
One animatronic in an escape pod, right? And of course our trackless vehicles, which have to recharge as they return to the show building.
So
@dieumeye mentions overheating - As I understand it the charging is all done wirelessly via charging pads in the floor. Anyone who has charged their phone on a qi charger knows that those things can get warm if they aren't lined up right, so that seems to be one possible issue.
@montreid I don't think the floor is electrified since charging is wireless. But things getting crushed under the vehicles seems like it would be problematic and possibly require a manual lift to get a vehicle moving again. Brushes around the outside of the vehicle just inside the lip to not wreck the theming might be a solution if they aren't there already.
@Mark_E - I keep hearing this 90 minutes to reset thing. But what are they resetting?
I wonder if maybe it is an issue with vehicles not charging correctly and getting stranded on the floor. There are places in the attraction where the vehicles go single file, and if a ride vehicle drops voltage or stalls out in one of these places...the whole system has to stop and then they have to move the vehicle out of service manually, I assume.
I also see in some of the ride videos that there are, in certain places, tracks on the floor from the vehicle wheels. It makes me wonder if dirt transfer from outside is having an effect on the floor chargers etc.
And, of course, the main chargers are at load, and then in the hallway back to the show building. If a charger goes out and needs replacing or maintaining, I assume it is not possible to do so while the vehicles are in movement. If at load, then they can take down one of the two loading stations. But if at return, I assume everything must shut down.
Has anyone been in a vehicle when the system went down?