About a week ago, I had bought a 4k from Best Buy, and charged the battery and went on a test flight to get a feel of the controls and make sure that I was comfortable how the aircraft operated. I went to a wide open parking lot and completed the start up procedures and lifted off in smart mode. I had absolutely no issues. I flew the aircraft at about 30 ft Altitude and went around the parking lot a few times. Landed it without issues, took off again and played around for awhile at 30 feet. I then went to about 100 feet altitude and again had no issues. I went from smart mode to angle mode several times without any problems. By this time, the battery was almost dead, so I brought it back home and landed without any issues. After a recharge, I lifted off in smart mode, hovered around 30 feet again, yawed to left and then all of a sudden the aircraft did cartwheels by itself and dropped right out of the air. I looked at the telemetry and it showed that I still had GPS signal. I have no idea why it would just flip by itself out of nowhere. The aircraft wasn't near any objects and the only thing below was just asphalt. The aircraft was only 50 feet from me and nothing was blocking the transmitter nor line of sight. All four props were on hand tight with the tool as they were with the previous flights. Does anyone have ANY idea what could have made this happen?