Don't understand your issue. The lift gate is powered up and down by a motor BUT because it's very heavy, there are what's called "struts" on each side (about 1 inch in diameter) They exert a force that helps lift the gate going up and resist coming down. There's one on each side. With time these struts loose their ability to supply force and need to be replaced. My experience is they last 3-4 yrs of regular use. However failure generally is slow, often worse in cold weather.
Also a gear could be stripped in the mechanism that powers the gate up and down
The struts cost about 20$ a set for hood or trunk (two different sizes) if they are the same as for the manual lift gates. If you replace the ones in the trunk, it can be a bear, I just cut small holes to get at them. No one the wiser if you are careful. The hood is quick and easy.
There's some previous discussion on the forum on changing the struts that simplify the process. Rather than cutting anything just peel back the rubber at the top. Reglued when finished. That gives room to remove the ball attachment.
Again I'm not sure of the poster's issue. I was just guessing the struts had gotten weak.