With the latest firmware v1.0.0288 for the Phantom 4, DJI have changed the way you would stop the motors mid flight. Back in the P2 and P3 days, some
idiots people managed to power off the Phantom mid flight by performing the CSC command ( used to power it on also ). All this is now changed.
In order to power down the Phantom 4 id flight ( in an emergency ) you now need to bring the LEFT stick to the bottom inside corner while simultaneously pressing the Smart RTH button. I am sure someone will manage to bring down a P4 by doing this accidentally but it seems DJI have listened to requests for the procedure t be changed to limit the stupidity of some people.