I've got one, managed to pair it with my T8-S and that's as far as I got. The instructions are complete rubbish, don't tell you how to use the Gamepad with it at all.
Hi
When it comes to gamepad pairing you can do next:
Turn ON the gamepad
Once it enters in sleep state,hold home button and blue light will start blinking.
When that happens gamepad is ready to paired.
Once paired it works properly with the box.
Also please take a note that besides charging gamepad with micro USB,you can also use microUSB to connect gamepad with the box,and in that case you can turn OFF gamepad,connect it with microUSB and use it as every other gamepad,on any device that you want!
Regards