Hi,
I don't have a CX2, but I do have a Blade CP. That happened to me after I crashed. The problem was the main gear was not flush against the gear on the motor. The motor must have come loose a little and it moved a bit when I crashed. I "reseated" the motor so it was flush again against the main gear, and it was airborne again. So give that a look.
Hope this helps!!
Joe