Help understanding what happened in the crash

Hi to everyone. My mini 250 apm +gps quad was going so much good but it was not able to hold the 45° angle and flipped. After some crashes I don’t know if I am able to find out the problem alone.
I think I need some help.

Vibration level in the safe range, no problem with compass gps, baro.

The crash happened during a sport LOS flight in stabilize mode. It’s configured as H QUAD. Compass calibration, esc calibration, compassmot I have dove everything and just the day before the last crash I did the esc calibration again one by one because in the previous crashes I noticed that after some test on the bench one (or more?) of the ESCs after some fast throttle variations went from 0 to a lot of throttle without an intermediate level of throttle: as soon as I rised the throttle for example 20% on the TX the motor went from 0 to 100% instead of 20%. Arming and disarming didn’t fix the problem. Unplugging the lipo and re plugging the lipo fixes the problem but after some throttle fast variation the problem was there again: I think this could have happened in the crash. The ESCs are 3x EMAX 12A and 1 HK-FIXEDWING 10A all flashed with BLHELI 13.2.

Last version of the firmware on the APM 3.2.1.

This is the point of the crash. I put some comments on it: … o.jpg?dl=0

I think that one or more motor gived up because of its faulty ESC.

Please someone correct me if I am wrong seeing the screen above from the LOG:

after a left turn I give pitch and full throttle for a fast forward flight. Almost immediately the quad flipped on its right side and crashed. As soon as I realized the quad flipped I lowered the throttle to zero.

Given this report of the crash. Can the bad ESC be the one on the left backward side of the quadcopter? (motor C in Mission Planner’s motors TEST, H QUAD).

Unfortunatly I don’t have the LOG of the motors. Just default+IMU.