The first time you use the ZXM-GIM20 it is best to calibrate it. 

Please ensure that you have your smartphone and gimbal charged, the App on your smartphone and that the phone is connected to the gimbal using Bluetooth (see QR code and instructions on page 13 of the manual). 

To calibrate the ZXM-GIM20, tap the calibration button in the App and wait for 15 seconds. The gimbal will automatically calibrate, turn off and restart.