Hi. Well. the first rule when operating radio control trucks, boats,planes, etc is that the controller is turned on first then the model is turned on. When you are finished the model is turned off first then the controller last.
The second rule is to make sure the fail-safe is set correctly. The fail-safe makes sure that the throttle does not go to full speed if the model looses radio signal from the controller.

With the Castle system if it is calibrated properly then the fail-safe will be set as well.
Make sure the ESC is properly calibrated with your radio system.