If the servos are responding, then your ESC is probably working. It will warm up a little due to the operation of the BEC. You may need to reverse the throttle channel in order to allow the ESC to arm. It must see "0" throttle before it will do so. Also, set the throttle trim all the way down. You may also need to perform an arming procedure such as going from zero throttle, to maximum, and then to zero again. Check the instructions for your ESC.