Until recently, I hadn't flown my P4 for a while so I set up an autonomous flight and it took off and flew to 46 metres (150ft), where it did its usual orientation when suddenly something happened and it crashed down next door.  I went in and picked it up and found a missing prop and another damaged in the impact.  It was a soft grassy spot and no other damage to the unit.

I tried to find info on a what tool to use to remove the three screws but none available from my search, so I had to order on spec, a hex screw driver that looked like it would work.  It still hasn't arrived so I dug though my jeweller drivers and found one that looked like it would work and it did.  It was a 1.4mm hex.

I had ordered two sets of mounting plates (minus screws), as I prefer to change all of them just in case.

The four spring plates were almost flattened and that convinced me to change all of them.  Those screws are tiny and I spent a few minutes groping through my hairy carpet before locating it after dropping it.

I'll have to do a few low level tests to make sure all is well before I send it off on the previous flight.

Hi. Thank you for sharing your experience and this informative post. With regards to the installation of a new mounting plates of the  drone. I would recommend that we have our DJI designated team to do the repair/installation for the said part to ensure that the drone is properly tested, diagnosed and installed with genuine DJI parts. Just a friendly reminder that DJI does not recommend doing any DIY repair since this will void the warranty of the said drone. In addition I will be posting a link ( https://www.dji.com/service/policy?site=brandsite&from=footer ) for more details about the warranty. Thank you and safe flying.