I have been running short experiments with Pixhawk 4 from Holybro on a Tarot X6 frame. Recently, an error led to a serious crash where the multicopter fell from 20ft. The landing legs and arms were replaced and all electronics appeared to be working after restrained ground tests.
Unfortunately, the first flight after the rebuild did not go well. Just after a stable take-off (position mode), the hexacopter flipped over at approximately 3-4 feet AGL. There were no observable oscillations or instability before the flip occurred. The pixhawk was reset to defaults and re-calibrated again. The motor/propeller configuration was triple checked. Then a second flight was attempted but the result was the same.
Unfortunately, I cannot diagnose the problem from the logs. Vibration does not seem to be a large problem. All PID values are at their nominal value under which I originally achieved stable flight before the crash. At this point I am guessing that the IMU sensors in the Pixhawk were damaged from the previous crash. Can anyone take a look at the logs and give me some ideas?