Sounds to me like the door interlock failed......
There is a set of microswitches on each door that unless closed, will not allow the car to move. It's not impossible to envision a bad switch, or one that is covered with gunk and stuck in the closed position, therefore not sensing that the doors are open. In such a case, it would never be a problem unless someone didn't make it completely into the car when the doors close.
Interestingly, there are a similar set of switches on the doors that open them when summoned. but only when the car arrives at the floor, closing the switches.......if these fail, when summoned the doors will open allowing someone not paying attention to step into an empty shaft......messy. Had that happen to me once in the Empire State Building.......fortunately I was paying attention.......
Complex electromechanical systems fail frequently.......however the inspection and building safety departments in NYC are infamous for corruption and accepting payoffs, and all work is (of course) union......
doc