While on vacation recently, I flew the P3 three times over the ocean without any problems. I had actually never had any trouble with it until I took it up on the 4th battery of the day (with lots of cool down in between). On the final flight of the day I took it up about 20-25 ft and it started "going crazy". It all but did a flip, turned wildly, dropped in altitude several feet, etc. I freaked out and thought maybe someone got the case too wet when we were jumping off the side of the boats. Who knows, really. I took it up later to re-test it out at the hotel while the first set of batteries were charging. When the problem re-surfaced 10 mins into the flight, my heart sunk. I knew she was done for. Then I came home and decided to do a little more in-depth investigation. I found two flights in a row that had absolutely no problems (35k ft distance on them, using them until they were empty). Then I tried a 3rd battery and she went absolutely nuts again, right away. Pulled it out, tried the 4th battery and it was fine. The DJI Go App shows nothing out of the ordinary on this particular battery. All cells look normal, right? I uploaded the logs to HealthyDrones, but again, everything looks "normal" on each of the screens. Even the battery looks fine, which is what I suspect to the be the problem given it only happens when I put battery #3 into the drone. Obviously, the easy answer here is to never use that battery ever again. It's only been used a total of 6 times (3 of which had problems, but I didn't realize at the time I had been using the same battery). Here is a video of what it looked like during flight. It's the entire flight (only 20 seconds long). As soon as I got it in the air, I hit record and let it continue until it touched down. I just wanted to share in case anyone else notices their unit suddenly goes crazy, without explanation. If you're lucky enough not to crash, try with a different battery. I would say I dodged a bullet (not crashing the unit) 3 times in a row.