Your gyro didn't initialize. Did you try it a few times? If there was no motor and to tail motor, your speed controller didn't receive a zero throttle position. Its a safety feature that will not allow the motors to start until the throttle is at zero power. Otherwise, as soon as you plugged in the battery it could start up. Why? You need to experiment a bit. Remove the blades for safety while you check things out.

By your description above, your battery seems like it is fine.