I have a new phantom 3 Pro. I have only used the simulator. Each time I start up I get the weak RC signal flashing, it flashes then safe to fly flashes then weak RC etc. I have done a IMU calibration and it fixed it 2 times so I could practice The 3rd time it did the usual and I calibrated the IMU and it acts like it is locked up although it says calibration in progress. Normal?