The gimbal on my P3P does not start when I turn on the aircraft  after changing battery, not crash etc. Drone flys OK and camer works but can't adjust gimal. - HELP

Did you remove the gimbal clamp?

Have you looked at the "flex" cables connecting the gimbal motors?

Yes I did remove the clamp, I had used on a previous battery but when I changed the battery the gimbal did not start. Everything looks OK including the flex (ribbon)