A couple of times I had embarrassing moments with "oh no black screen" or "oh no white screen" and it was the dial RH side had got spun taking it out of the case!
Batteries do have firmware too, do you know if they are both on the same?
I wouldn't have thought that could cause problems with the camera though. 

It's not unusual to have a minor glitch when you start up in the field.
Turn everything off and start over.
 Usually this happens when you wanted to quickly demo it!

Best sequence for me is
1) Turn on mobile device but don't open app 
2) start controller and connect the USB
3) start phantom
DJI Go opens automatically and you can go to camera view.

I notice sometimes if you have the app open before connection establishes it doesn't always link properly.