Problem Description:The power switch is on, but the upper digital display does not light up
Reason Analysis:
1) The AC wire connected to the controller of the power switch is loose
2) The controller burnout
3) The communication cable is crushed and damaged / the communication cable terminal is loose
4) The upper digital display is damaged
Solution:
1) Open the motor cover, and plug the AC wire connecting the power switch to the controller tightly.
2) Replace the controller.