As much as you have gone though, and with the truck you have which includes a factory brake controller...
...yank all that surge brake crap off and go with EoH. You will be miles ahead, and have a 10x better braking system.

Are you sure you have the bleed-off tube lock-out solenoid?

You have to be sure you don't have the brake actuator compressed before shifting to reverse and activating the lock-out solenoid, or else you are going to be locking the brakes actuated. If the trailer has a 5-flat it should be the blue 5th wire running to the actuator, as you said it is.

Pictures of the set up would help for troubleshooting.

That is exactly what I think is happening. The trailer is pushing down hill towards the truck. When I put the truck in reverse at that time and attempt to back up, the trailer did move but I think the solenoid fried at that time! Once I get this repaired, I am just going to use the lockout pin hole in the actuator until I get on a more level surface and all should be fine. When on a flat surface, the actuator is not compressed and the brakes are free and backing up is fine. Again, I think this is the problem. Tie down manufacturing has "STILL" not returned my calls! Not impressed with them at all!!!