Can't regain manual control

I am using a Phantom 2 Vision+ V3 and a Galaxy Note4 phone. Also tested using another Phantom 2 Vision+ V3 and Galaxy S5 and both tests reveal we can NOT regain control of the Phantom during a Grid Mission. I was doing some testing in an open field with 9+ sats locked in at all times. I 1st tried switching the S1 switch to the down position and it just continued to fly the mission. I had no control over the Phantom. I then tried powering down my controller/wifi extender/everything and the phantom continued to fly its mission. At this point I have no way of taking over manual control. I really need this to work. Any advice?

Repeatedly switch to the top of the S1 button
将S1按钮反复切换至最上面