I've just done a controller calibration as usual - USB link to PC - and now I can't start the Quad by pulling both sticks down to the left and right corners. The last time I did a calibration last week, it took two tries to start but all was OK.I have neen trying, unsucessfully to install Ground Station, I have the suggested hardware but I'm told I don't need it if I have bluetooth on my laptop or iPad; if that means anything to anyone. What is going on here? C.