Flew my Platinum a little this weekend. Everything went OK except I noticed that the altitude on the screen was way off. It would say 22 feet when I was looking at it at eye level. Went the calibrate the IMU (don't even know if that's the issue, but I did it anyway). The bar that shows the % completion of the task goes all the way 95% across the screen then stops. Says it's still calibrating but it's hung up there for 30-40 minutes now. What's going on?