Hiall,  We have just had a massive crash of our P3  and it totallytrashed the camera. It fell out of the sky from 20m up.

Wehave up dated to the latest firm wear so that we can do mapping using Pix4d andDronedeploy.  We were doing a gridmission using pix4d and the phone app crashed. We rebooted the app then triedto take control using the RC then the droned just turned itself off and fellout of the sky.

Hasanyone got any ideas of what went wrong?

would need to see the craft logs, upload them to health drone,

what was you battery capacity at take off ?

Battery was fully charged,  How do I up load the log?  the DJI app was not running at the time ,  only the pix4d app was running

I am not sure the logs will reveal too much but certainly worth a look however I'd be concerned in what you say because:
1. App crashed
2. Your drone must have still been flying? Because you state you rebooted the App. So there was a time when your drone was flying or hovering at its location. Was your drone in LOS?
3. If so could you control it with the RC before you rebooted the App? Was your RC LED green.
4. I'd say if the drone was flying or hovering while you rebooted your app then the fault  was not with your drone but some communication between the app and the drone when you rebooted.

Sorry for that terrible crash ! Please contact your local dealer and send it for a repair . You can request a data analysis for that crash .