I had this happen the other day. During my call to Yuneec it was established the ST-16 had lost calibration. Best way to verify this is to call Yuneec and speak with a customer service rep. You really should do that first when you have issues like this.
Remove your propellers.
Turn on ST-16 and the H. Both must be turned on for the following.
After both complete the boot up process tap "system settings" on the ST-16 to exit telemetry mode. Hit yes.
Go to "About Controller"
Tap About Controller rapidly about 5 times or until a hidden menu appears.
Scroll to "Calibrate Test". You'll get to a screen that says "Step 3" Calibration" that has 7 orange squares with labels that correspond to control channels.
Center the pan knob and tilt and speed sliders on the ST-16. This is VERY important.
Tap "Start"
Cycle both sticks in all directions, top, bottom, sides, until some squares start turning green.
Cycle the tilt-speed sliders from top to bottom, and the pan knob stop to stop and back to center until more squares turn green.
Don't leave the page if all the squares are not green. You missed something if they are not.
That should complete Page 3.
Push "Next" to get to the next page, it has a lot more orange boxes. On that page you will cycle every button, switch slider, knob, and stick on the ST-16, including the motor arm, shutter, and video buttons. You also need to push the useless button next to the OA switch. It actually is connected to something, but what that is we don't know. Be certain to go top to bottom, side to side and push every button. Each control must achieve its full range of motion.
When all the boxes are green push finish and exit the calibration screens. You will need to hit the return arrow tab on the ST-16 several times to exit completely back to the main screen. The blue light will remain flashing until returning to the main screen. The blue light should stop flashing and the beeping should be stopped after returning to the main screen.
Now go back into system settings to make sure the ST-16 is still bound to the H. If the above didn't work, call Yuneec before trying to fly again.