Cannot locate the Sync3 USB module in the Service Manual's wiring diagrams; only Sync1. But my
guess is, Sync2/3 it run back to the APIM. The APIM is bolted to the FDIM which is the display.
Computers will deactivate a port that has problems with power; and the only way to reset the port is to deactivate the computer. Let's make sure that isn't the case here, since the alternative might involve testing the wire harness before replacing the APIM.
Disconnect the harnesses seen in the photo... (The top one is power and I suspect the middle is USB but not 100% sure)
... then disconnect the vehicle battery for 20 minutes. Once reconnected and ignition activated, test for the presence of 12v on the pair and 5v on the quad while the harnesses remain disconnected. It's possible that the third one may actually be the USB... don't recall as it has been awhile since I've been in there.