To my fellow F550 owners: I purchased a F550 combo ARF package from Atlanta Hobby three weeks ago with Naza V2, GPS and Zenmuse. I've spent the last few weeks carefully assembling it after thoroughly following DJI's instruction and watching dozens of "F550 build" videos on YouTube. Over the past two days I hooked up the ship to my NAZA software several times and checked and adjusted all settings, parameters and calibrations including "motor test" as per the instructions. (I own two P2's, so I'm fairly familiar with Naza set-up procedures) Today, satisfied that it was "All systems GO for launch" I went to my flying field, rechecked everything again, did my compass dance again, and then disaster struck - Upon initiating motor start sequence, one ESC burst into flames and all six motors smoked! I initiated motor cutoff within maybe 1.5 seconds, but too late. All motors and ESC's are toast. Now here's the strange thing: I have been using the same, brand new MadDog RC 3S 5,000mAh LiPo for all of my Naza assistant tests and everything was fine. After the fire, I went home and hooked up to Naza assistant again and surprisingly, the Naza board and Futaba receiver and all electronics are fine. The only things that fried were the motors and ESC's. I can't find any short-circuits or burned spots anywhere on the frame or any of the wiring, anywhere. I've just boxed up the whole rig, as is, and shipped back to Atlanta Hobby for diagnosis. I'm at a loss to figure out what caused this. Ideas anyone?