i turn on the dji app and the signal to the controller is great with all the bars, but the video signal is weak at 5 feet with no bars showing and a red banner in the middle stating weak to no signal, although o get a live cam view ,, it has never been off the ground, it has all its updates, ,i get 11 sat,s all green bars for the controller, i checked the sd card?, even let it warm up for 10 minutes, so i shut off the dji app and went to the app store and got the litchy app paid for it, and oddky enough, it wil not even connect, i have a green light on the bottom side reset button,

     Are you inside, take the aircraft outside.  Also what device are You using ?  If you can , make sure it is in airplane Mode.    Make sure you are using a compatible device.  I -pads work great.  Did you update both the Aircraft and Transmitter as well( Pro or Advanced)  ?    Make sure your antennas are not crossed if a pro or advanced.
Is this a brand new machine?  Have any Modifications been done to the Antenna ?

Try these suggestions out.  I hate to start doing anything drastic, lets  start conservative.  Maybe others can chime in

Let us know.  By the way is it a Standard or Advanced / Pro?  The standard works Differntly than Advance or Pro?

Cheers - donnie

I've had this happen many a time.

Do an IMU calibration or two indoors on a very level surface.
Restart your device before launching the DJI Go App (every time).

That should help...it always fixed mine!

Reinstall the DJI Go app as the next step if those two don't work.

Please try to stay away from other 2.4G interference, and try different open filed to test it. Also, don't fly it directly above the RC since it's a blind spot of the signal. Adjust the RC antenna and make the side of it face to the landing gear of the aircraft.