I pinched my cable between the WDH bars and trailer while 90deg parking (forgot to pull the bars before backing into storage). I blew a fuse on the TV as well and it took me a bit to realize it was not the TT but rather the TV. I plugged my 4pin trailer light in to test the TV.
I have a question for you. I went to the RV store and bought a replacement cable but they had no idea what I was talking about when I asked for the grey strain relief that goes in the junction box. I had to split mine to get it out. I see on in the photo you posted that I have the exact wiring/box/strain relief as you and wonder how you procured a replacement strain relief.
2016 Cherokee 264L
2013 GMC Sierra Denali
EAZ Lift 1000 WDH w/Sway Control
2016 Nights Camped: 20 Trips: 7