I reinstalled os, apm. and Calibrated compass, accelerometer, radio, esc. I did not do anything else. but I can't fly my erle-copter. even with maximum throttle. and from previous experience, even drone can fly, it does not maintain it's pose and position. it goes away to one direction just like autopilot does not work. I'm struggling to find out how I can fly and control drone for 3 weeks. and I didn't measured drone's weight. but I think it definitely lesser than 1.5 kilogram. erle-copter + gimbal leg(without camera) + gps.