short circuit code on brake controller with no trailer connected

how's it going all.

I had a shop install a redarc brake controller on my 2022 trd off road. it worked for one day and then it was showing the code sequence for a grounding fault. our trailers turn signals, brake lights and running lights are working fine, but the trailer brakes are not working. I thought it might be my travel trailers brakes, but when hooked up to another tow vehicle they are working perfectly fine. I took the truck back to the shop and they installed a curt brake controller, thinking the main unit of the redarc must have been bad. still, with no trailer connected, I am getting a short circuit error code. the wiring for the brake controller is done correctly and it has a good positive ground location.

has anyone else ran into this problem before? I'm wondering if the wiring of the truck itself is messed ups somewhere between the factory pigtail and the 7 pin. the dealer is going to have a look at it tomorrow as I'm still under warranty.