Rear hatch lock actuator failed when connected to trailer.

What is your question?

I replaced my failed rear hatch lock actuator a few months ago. It just failed again and I believe not the failures may coincide with my trailer being connected (though not positive and hard to replicate without burning through a lot of money). My question is: How can I validate if there is an issue with the electrical on the vehicle (maybe the aftermarket brake controller), or an issue with the electrical on my trailer, or neither? I'm not very good with electrical systems, though I know how to use a multimeter and can probably figure out the pinouts on the trailer connector if someone can tell me what I'm looking for.