Is auto takeoff working for you now? There's a couple of threads about the motors shutting off after launch and the Mavic falling to the ground on the last firmware.
Auto launch working fine with last firmware so far for me.
One time I made mistake. I was holding very far from centre of gravity and didn't let go when its started launch. Its started to flipping around nose and in that moment motors was stopped automatically.
I don't know is it was the same thing with motors shutting, but auto shutting helped me from crashing drone.