Each Locker bank will have a single controller located in the kick underneath the lockers. The kick should be easily removable as this is part of the joinery specification. Once the kick panel is removed, the controller will be found more or less directly underneath the position of the Kiosk unit. For tile or side mounted kiosks the Controller will still be located within the locker kick however within 2 meters of the Kiosk location.
Locate the Black USB cable going into the controller -there is only 1 black USB cable going into it. Unplug this cable, wait 5 seconds, then plug it back in. If the controller has provided power to the card reader it should make a single beep.
The card reader should make a single audible beep when it is reconnected to the Controller.
Swipe a card that is known to work against the card reader and watch for the Kiosk to respond. If reader beeps then try once more. If Kiosk still does not respond then try one of the alternative solutions:
Troubleshooting frozen iPad kiosk panel (restarting kiosk fs app)