Are you able to bind the new T8 transmitter to the quad? that's first step, I want to say with tinyhawk in general can use the bind_rx command in the betaflight CLI to trigger it into binding mode instead of trying to hold bind button while plugging in a battery (a job for a man with three hands). Would also suggest hook the quadcopter up to computer with USB and get it connected in betaflight (easier said than done but usually just matter of getting the "right" USB drivers for your FC so Windows can find it as a serial device). If able to get it connected to betaflight can head over to the receivers tab and debug what's happening with the input there or might need to go to the modes tab to change which switch being used for ARMing and all. Getting used to OpenTX on the transmitter side can take a while too I still get lost in the menus sometimes but if have it connected to computer and seeing the received signals is a lot easier to see what effect your changes are having on the receiving side of things.
