The ST16 is the brain of the Typhoon H system. Most ST16 problems fall into three buckets.
Stick calibration
If the drone drifts or a stick does not center, recalibrate the sticks in the ST16 settings. Do this on a flat surface with a full controller battery.
Signal loss
Short range or dropouts are usually antenna problems. Check that both antennas are tight and undamaged, and pick up genuine replacement antennas if yours are worn or loose. Aftermarket range mods exist but start with the basics.
Binding problems
If the ST16 will not bind to the drone or camera, confirm both are on matching firmware, then run the bind procedure with the camera powered and close by. A failed bind after a firmware update sometimes needs both units reflashed.
If the controller has physical damage, a bad touchscreen, or will not power on, that is a repair: controller repair.