If you don't have a KT controller, I doubt that it will work.
For reference:
Red is from battery positive (36v)
Blue is switched battery voltage to power the controller
Black is ground
Yellow is tx or rx data
White is rx or tx data
If you connect the red and black, it'll switch on and show the correct battery voltage. You can turn the pedal assist up and down, but nothing will happen if it can't transmit or receive data from the controller. It won't show the speed either because it gets that as data from the controller.
This was my thought as well, so I have ordered me a KT controller, installed it, was some cable fiddling still, and now everything fits and works perfect, it is a good digital invention.
Finally, I compared the cables from the ReaseJoy controller, and what I realized is, that the controller would have fit as well the KT panel, but the ReaseJoy controller doesn't have the recuperation mode, so I was gone for the recuperation controller, and my first impression of this recuperation feature is a positve surprise, a surplus of power and distance, therefore I can recommend that controller.
I even managed it to adjust my old PAS to the KT controller, just loose the pins and connect black to black, the other two cables, just give it a try, it will work latest with the second round.
Have fun.