No wonder the generator was breaking down.
THE WHOLE INSIDE OF IT WAS LOCKED AWAY!!!
Probably the dumbest thing about this movie. The builders made a generator which kept the city alive yet they locked the door so nobody could get inside to fix it.
Also I found it funny that the "mechanism" to start the lifeboats coming out was big wheel sitting out in the open. If the builders wanted people to stay down there for 200 years then why did they put the gear to start the evacuation process out in the open for anyone to turn. It's amazing that in such a long time nobody ever bothered to turn it.