I have been recovering for a hip replacement so today was my second outing flying the P3P since I first received the unit. I had upgraded the software and was not anticipating any issues. I did the preflight checks including compass calibration. I started the engines and all was well. I elevated up to about 3 feet and then tried to hover. Next thing I know the P3P seemed to have a mind of its own and accelerated very fast and climbing quickly. Unable to stabilize I tried to stop the engine while trying to get it over grass . Ended up crashing into some high grass and the battery popped out. Cleaned the props and put the battery back in. Everything looked ok. Calibrated the compass again and this time I had no problems on take off of during the flight but must admit was very scared that I would lose control again. Anyone have any ideas of what may have caused my problem on take off? Thanks.