First, make sure the fuse is not blown.
Second, there is a reset button on the 7-series. Looks like an inverted triangle to the left of the ATT button. Make sure you unplug anything that's plugged into the USB port before doing a reset.
The reset will restore all settings to factory defaults, so you may have to readjust the screen angle or other settings on the Kenwood setup screen (everything on the Garmin setup screen should be unchanged, but check to make sure) if you changed them before.
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