How to judge the fault of the access control system

The phenomenon of access control failure generally has the following situations:
A: There is no external power supply for the access control system (the electric lock does not work, and the power indicators of the controller and card reader are not on);
B: The access control controller is faulty (the door cannot be opened by swiping the card, and the controller indicator does not light);
C: The access control electric lock indicates a fault (the access control electric lock does not work and the door cannot be locked);
D: Access control card reader applaud (cannot read card, no response when swiping card);
E: Access control line problem.