Jjrc x1

So I finally managed to sort out my Devo 7 update programmed set up and working perfectly
And then disaster One of the rotors front right hand side decided to stop working it turns on and synchronises with the controller but when you give it Power The motor twitchies then starts bleeping whilst the other rotors are all spinning can anyone tell me what I could of damaged it's trying to work
But then it shuts itself down would really appreciate some help