Mine was working fine from day one and still fine. Have you tried following the instructions manual? See if one of these helps:
Note: In case of extreme slopes, the tailgate may
not be electrically opened or fully closed due to the
change of centre-of-gravity position.
If the tailgate fails to be properly opened to preset
height or fully closed, manually close it once slowly
and completely to recover the functions of power
tailgate system.
Note: During manual operation of electric tailgate,
avoid violent or rapid operation, so that the electric
tailgate system will not be damaged.
Opening Height Setting of Power Tailgate
Users can set the opening height of power tailgate
as needed by using the Close button at the tailgate
or the entertainment display. The power tailgate
controller will record the new opening height.
Setting method 1:
1 Open the tailgate to desired setting height and
keep it stationary.
2 Press and hold the Close button at tailgate for
more than 3 s, the buzzer makes a sound to
indicate the successful setting.
Setting method 2:
1 Turn on the entertainment display and select
'Vehicle Settings - Comfort and Convenience -
Tailgate Opening Settings' in sequence. You can
set it to low, medium or high position.