Get it to a reliable trailer shop.
On ours, I think, there are two heavy gauge wires connected to the battery
"+" post, each with an in-line 20amp fuse. One wire runs all the way to the 7 pin connector. The other goes through the firewall to the brake controller, with a connection to the brake light
switch - that triggers the trailer brakes
; via the second wire to the 7 pin. Depending on how well your TV frame is grounded, you may also need a separate ground wire from the battery "-" post to the 7 pin.