BCM keeps burning up and taking the tailights, parking lights and key fob out

Noticed the key fob and various dash lights not working about a month ago. Took it to the Toyota dealer and they said it was not the fob (I already replaced the batteries), but the truck would not program. Took it to another shop who disconnected the aftermarket parts (trailer 7 pin harness-piaa lights-tailgate lock-gauges-trailer brake and tailights assemblies, thinking these were the culprit. Nope, burn up another BCM. They put another one in (3rd) and it worked for several hours until they plugged the ac "magnifier" back in and burned that BCM up. They told me to take it back to the Toyota dealer.

The Toyota dealer looked at it and said I need to put in new OEM tailights to replace the non led ones the other shop put in and put in a new BCM and then do an ohm test on every single wire until the BCM burned up. I then took it to an auto elec specialist who said his equipment couldnt communicate with the BCM, which I've learned wont communicate with anything, MIT either works or. Burns up at $550 a pop.

So I've hooked back up the piaa lights because the headlights they are hooked to have always worked. I've hooked back up the gauges as they still work plugged into the obd port. The key fob still does to work as well as various dash lights (ac control lights/radio buttons) and park lights, but brake lights do.

I've bought new led tailights and a new BCM. What else should I do to fix this dang thing before installing and possibly burning up this new BCM?