If you're good with a soldering iron, you could take the power input plug off and have those wires tie in at the board solder pads where the RX connector hooks up. That should get you to 'rx voltage' 4-6v from the bec, instead of full 'battery voltage' you were putting in.
If you're bad with soldering iron, splice a servo lead onto the input plug wires, so it can connect to an empty slot in rx, probably remove the signal wire so it's easier to remember it's not the control plug
I haven't found a video on that thing yet, since that seems to be the only way to find out how these 'Orange chicken with fried rice' brand parts work.
This seems to be the light controler that you have coming
https://youtu.be/85woXq-5OGg