The speedup to twice as fast as it had gone during the rest of the flight is odd.
It’s all gonna be speculation at this point for us, even if parrot figures out exactly what went wrong, what are the odds they’d say what it was anyway? They’ll probably just replace it after confirming nothing shows user error.
Still, I like to make uneducated guesses, so here’s my thoughts:
An esc problem would cut all four motors at once, and you’d just lose altitude, not fly off at double speed.
Single motor failure and you’d probably get an error and again, falling down.
I think the ground speed is calculated from gps positions, so either
something went wrong gps wise and your drone started thinking it had jumped a lot over to the left or something, tried to correct and dropped a little altitude then error cuts the motor, or
Something went wrong with the pitch or roll sensor, or even just the calibration, and the drone started to think it was leaning when it wasn’t. Drone thinks it’s flipping, tries to correct, loses some altitude until it overcorrects and flips or just thinks it’s flipped and error, cuts power.
