I've been doing some digging on this. I've found that the Marshmellow release has many bugs with this being one of them. The DJI GO App in my case worked fine with the 6.0 Marshmellow updaete; however, when I downloaded Litchi and tried to fire it up, It didin't ask "just once, or always" but it did ask "which one would you like to use". Neither would connect. Had both apps on my Samsung Tab S with Lollipop. Both worked perfect asking "just once or always". I delted Litchi to leave only one primary app GO. After doing this, GO worked fine again. The issue I experienced is what I belive to be a bug in the recent 6.0 Marshmellow release trying to figure out which app to use as primary. When it can't determmine this, it doesn't pull up either. Fix for now is, wait for a fix, delete one or the other apps (I didn't delete GO because of all the previous data accumulation and propietary stability with DJI), or get a former device with kitkat or lollipop on it as a dedicated device. For now, I'll have to do without Litchi until a Fix arrives. I really needed this but the path of least resistance is to stick with GO and wait for a fix.