Trailer brakes not releasing

Lost two tires on my trailer today, just dropped off track hoe everything was fine, not 5 blocks away and i'm getting pulled over cop behind me and watched my 2 tires blow out from brakes not releasing. I recently got the trailer, no idea on history, but 5 tires were in rough shape, 2 of the ones that blew, so pretty sure this was not the first time brakes had an issue.

What could possibly be the issue? Only one side did it, and even getting it home after, the brake on that wheel never...

Trailer brakes not releasing

Trailer brakes not releasing