trailer brake issue

[29racer]

Trailer brakes locking up when in reverse. I have checked the power for the reverse lights and it has power going to the bypass on the trailer but they are still locking up when backing up. I assume the bypass valve is bad but this started when I had a buddy back the trailer in to load the boat and he unhooked the lights first, ever since then it has been doing it. I was wondering if maybe there was somekind of trick to reset it or if it was just a coincidence that it stopped working then. Still under warranty but dealer is 2.5hrs away so any help is greatly appreciated.
Thanks,

[NewmbaTX]

Probably just coincidence...Check you wires and connections again. You should be able to hear the solenoid "click" if your at the hitch when you put in reverse. no click , no power, maybe a pinched wire, little corrosion on the blade in the 7pin..Or a bad solenoid.

My connector to the vehicle does it every time on first connection, just a lillte wiggle and good....Remember, a good "ground" connection is required too!