The wiring of the button runs through the service desk itself, but it was recently and rather roughly installed, with little bits of sawdust sticking out of the freshly cut and drilled slot for it. It clearly isn't a standard feature and is instead a modification. There's no exposed wiring aside from a little peek of standardized cables running through the hole.

At the end of the 48 hours, when the doors unlock, the mannequins go still, and the employees wake up, Norton (if he returns to the service desk for one last look) may notice that the button has completely returned to its undepressed resting state.