Why is my Trackpad sticking when pressed

I have a Asus Vivobook 14 Flip TM420IA-EC110T and when i press on the bottom left or right of the trackpad it will stick down and i need to press on the surrounding plastic to unstick it. I have opened the laptop and there is nothing inside cause the trackpad to stick or blocking it as far as i can tell. How can i fix this?