I have been struggling with this for a few months on and off but I have been at it full on this past week and I have got nowhere!!
I go through all the usual steps and after the long monotone note, I press the arm button and noises are made, wait for them to stop then move the throttle down to low and it is recognised,THEN the strange bit, about 10% of the time 1 of the motors will correctly calibrate. I have had 2 motors correctly calibrated at once as my personal best and all of the motors do spin they just do it in pairs! I would really appreciate any help any of you can suggest.
This is my set up as it would be useful for anyone who could help:
Tunrigy 9x + the encoder that gets it to work on the pixhawk
4 Turnigy D2836/9 950KV motors
4 HobbyKing 30A UBEC (http://www.hobbyking.co.uk/hobbyking/store/__15205__Hobby_King_30A_ESC_3A_UBEC.html)
3DR power distribution board
1 Turnigy 2200mAh Li-Po battery