I had been flying my iFlight DC5 FPV drone for about six months.  Had a light crash (nothing broke) however I went out today to fly but there was no video image.  I did see the OSD info laid over the DJI logo.  The night before I updated the firmware on all my units.  I did a rollback and checked again, no joy.  Put them back to the newest firmware.
Fortunately I own two air units.  I swapped the cameras on the air units which showed the camera was the culprit.
Before looking to buy a new one I took the back off one more time.  I noticed there is another ribbon connector under the foam block.  I disconnected and reconnected it, put the back back on and powered up the system.  
I was very pleased to see a video image in the goggles!
The picture below shows where the other ribbon is.

If you have no video check this plug out before sending your gear back to DJI.

Hello there Hummingbird.UAV. Good day and thank you for sharing this interesting information with us. Have a safe and a happy flying always.

THANK YOU SO SO MUCH!!!  I just bought a second hand cinewhoop for a work and when I tried to connect the air unit with the googles I saw it conected but only the logo on the screen, I tried multiple things and no one worked for me, but this was the last forum I saw, I tried it and… IT WORKED!!!

djiuser_GMDF4SfuCVfa Posted at 1-14 14:00
THANK YOU SO SO MUCH!!!  I just bought a second hand cinewhoop for a work and when I tried to connect the air unit with the googles I saw it conected but only the logo on the screen, I tried multiple things and no one worked for me, but this was the last forum I saw, I tried it and… IT WORKED!!!

Great, I'm glad you were able to fix it.  Happy flying.