Good luck with that. I have the same problem and nothing that dji has told me workes. they keep telling me same things over and over. They say go to the app and click camera how can i click camera when i cant get on the app they told me to uninstall the app and reinstall it done that. they told me to link my control. The control links to the drone i can fly the aircraft i can control my gimbal i just have no video. I'm thinking the usb board on the control is bad im going to replace it and the ribbon cable for usb. I will post if it works .
DJI support instructions are incomplete. In order to select "Camera," you have to choose either the Inspire 1 family of drones or the Mavic Pro (see screen shots below). Any other selection nets "How to Connect." This option takes you to an instruction page, but not the app. So if you select the Phantom 3 Professional, you won't get the "Camera" option. You will get the "How to Connect" option.
Here are screen shots of the DJI Go App while NOT connected to a drone.
To open the app, pick your bird. Select "Camera."
Inspire family nets "Camera" option:
Mavic Pro nets "Camera" option:
Phantom family nets "How to Connect" option:
Instructions for connecting the Phantom 3 Professional:
Matrice family:
Osmo family:
Once you select "Camera," (via Inspire 1 or Mavic Pro pages), the Go App opens:
If you can't open the app after getting this tsunami of information, then I highly suggest another hobby....<;^)
Good luck.
D