Welcome to the forum
If the KeyTV module light comes on when you disconnect the coax from the roof antenna, I would suspect a short in the coax or antenna.
Your antenna is “powered” through the coax and it only takes a single strand from the shielding to short it out. I would be looking at the coax ends, but it will have to be disconnected from both ends.
Removing the 360 from the roof isn’t difficult, you just have to peel back the sealant and replace it.
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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.