Welcome to the forum. You need a Volt/Ohm Meter at this point. GFI plugs will have 2 sets of Romex, one is “feed” and the other is “load”.
With both sets hanging in the breeze, turn on the AC power and using the meter, determine which set of wires is “live”.
TURN OFF the power, now look at the back side of the gfi plug, it will be marked. Put the previously LIVE set on the LINE side and the other set on the LOAD side. You will have to turn the power back on to reset the GFI.
2012 Copper Canyon 273FWRET being towed by a 1994 Ford F350 CC,LB,Dually diesel.
Airlift 5000 bags, Prodigy brake control, 5 gauges on the pillar.Used to tow a '97 Jayco 323RKS.
Now an RVIA registered tech. Retired from Law enforcement in 2008 after 25+ yrs.