1. Does it work on the ground when you turn the machine off heading?
2. Does the led stay solid when you turn on?
3. Does the rudder stick work?
4. Are you solidly plugged into tx channel 4 and 5?
5. have you tried reversing the gy401?
6. Your gain should be 75-80.

If this all checks out, you should be good to fly. If you think it checks out, and it still rotates, you have missed something.