As far as I know, these things, fed by 12 VDC from somewhere, route that signal to the various sensors through the switches. Since nothing is working, it is either 12 volts going to the box or the box itself. You might pop the thing out of it's mount/box, and check on the connections behind. A check with a voltmeter might indicate if you're getting power. No power - chase the wire. Power OK - replace the box.
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