Well, today has been the Phantom day from hell. I couldn't sleep last night thinking about this problem and got up at 0430 and started fooling with it, trying to figure out how to change the battery limits. The assistant software absolutely would not let me access the aircraft unless I did the firmware upgrade, so I thought, to hell with it, I'll give it a a shot.....what's the worst that can happen? Well, I found out ! The download seemed to go okay, I changed the limits on the batteries and took it out for a trial. Takeoff normal, hover normal but when I backed it up a bit, it just kept going and before I could react it was heading toward the neighbors garage so I got it on the ground where it flipped over and mowed the grass. I picked it up, recycled everything and tried again with the same result. Third time I just let it hover and it was drifting all over the place. Thinking that I had somehow turned on the IOC, screwed up the IMU or messed up the compass I went back in and tried to recalibrate everything. Long story short, I couldn't do anything...the controllers wouldn't cycle, the IMU wouldn't calibrate and kept getting a message the there was an error of disparity in the controller setting and I needed to recalibrate the transmitter. After fooling with it for half a day, I finally got through to DJI support who talked me through getting everything reset. While I had him, I went through all the values and everything was, in his words, excellent. When I went outside, I calibrated the compass successfully, and lo and behold, it wouldn't start...nothing. Back inside, go through everything again, and after several more tries, and transmitter calibrations, I got it to start. Back out side, normal startup and same thing, give it a little forward or back and away it goes. That's where it stands right now...I had a perfectly performing Phantom, did what I was advised and now I have a Phantom that I can hardly control. I sure wish that I had followed my first instinct and left it alone but it's too late now. Sorry to be so wordy but I had to describe what happened. Any ideas, comments or suggestions?