Just done my firmware update to latest and did a Imu calibration when cold. The battery was at about 35 % when finished doing the calibrations so I took off to check for motor vibrations. Soon as I got in the air I got the critical voltage red warning and the motors cut out ( I had my hand lightly on the leg so I stopped it from a crash) the battery level was at 26% so it should have been ok. What do you think the problem was.