Need help, my uav doesnt work properly

Hello guys,

I have a problem with my apm 2.8. when i change the flight mode to auto mode, the plane will go down with full throtlle and when i try to recover it with elevator stick input (pitch up) the plane stucks, and won't give any response..

is there anybody who can help me? here is my hud vidio and graph log from my mission planner