This information is from 2012 factory service manual. So it may not be the same for yours. Use it at your own risk. The wire going to the button above the license plate has two pins. Pin 1 should be a green wire and have a voltage on it. Pin 2 is a yellow wire and goes to the liftgate control module located under the left side rear panel. The module has three cables going to it A, B, and C. The pin 2 yellow wire should go to connector C - 13. The connector may not be numbered and hopefully there is only one yellow wire.
Troubleshooting: First take a meter and measure from ground to pin 1 and see if you get a voltage reading. Then connect the cable to the switch, back probe pin 2, push the button and see if you get the same voltage as on pin one. Next take off the rear side panel, locate the liftgate controller, locate connector C, find the yellow wire. Then continuity check the yellow wire from pin 2 on the switch to the controller pin 13. Next with the switch connected see if the voltage is at pin 13 by back probing it and pushing the button. If everything checks ok, but it still does not work you might have a bad controller or connections to the controller are bad or some safety connection is not satisfied. The controller is connected to the CAN networks so they can disable it.
