In proper theory the mechanical endstop switch itself SHLOUD be wired to common and NC. This is important for self diagnostics.


If the switch is wired to NC when you send the home command if the switch is unplugged then the printer will not move that axis or it will move it a bit in the opposite direction of home and then trigger an error.


If the switch is wired to NO the circuit is naturally in an open state and the controller doesn't have the resolution to know if a fault is present so when homed it will crash the carriage into the gantry frame expecting a signal to show up at some point.


For self diagnostics it is far better to have the circuit normally Closed and open when the switch closes. No matter whether you are doing it with power or ground.