This has happened to me twice in the 10 days Ive owned my Mavic. Drone would not start and home screen displayed "aircraft disconnected". I searched everywhere and tried everything for a solution and found it hear buried way down the list, but I think it's important to state again, especially for those with big fingers. Apparently when ejecting the SD card my finger moved the switch close to the card from RC to WIFI. When I put it back to RC all was good. I wish DJI would move that or find a way to lock it as I don't think scotch tape will work!