I'm a newbie that's done tons of research, gone to two RC hobby stores for advice, and I'm still stumped, especially considering that DJI no longer supports this drone, and every link I can find goes to dead pages on their website.  I'm sorry for the long post, but I want to make sure I include everything I've done so I'm not missing anything or wasting your time.  
I recently got my first drone, a Phantom 2 Vision +, and my main problem is two-fold.  

1) It flies, but blindly since I have no live video to the cell phone app, which is "Litchi for P2".  Where the live video SHOULD be is just a totally black screen.
2) The left silver thumbwheel on the controller moves the drones camera straight down to the floor quickly, but in order to get it back to normal front facing, I have to "pop" the left dial over and over, moving it in small incriments.   Both hobby stores agree that the drone itself is probably not the problem, because when it boots up, the gimble has full control, and as you move the drone around (props off) with your hand, the gimble correctly moves to keep the camera still. I'm going to try to link a yuotube video that I just shot showing you what I mean.  They both told me to update the firmware, which I tried unsucessfully, and is what brings me here for help.

To update the firmware, I installed the "Phantom 2 Vision Assistant".   I tried multiple versions as I got stumped, but the current version is 3.8
I plugged the USB from my desktop into the drone, and also tried plugging it in to the controller as well, but neither works. I also tried having them both on, as well as the wifi extender, or having just the device that was plugged in to the USB on and the other off.  In every possible combination, when I click on the "upgrade" button in the Assistant software, there "should be" a list of items, but mine is blank.  It's as if the drone (or controller) aren't plugged in at all, yet I've tried both.

When I click on the "Phantom" button at the very top-right, or the "upgrade all" at the very bottom-left, I get a pop-up saying "Connect to the controller".....even when the two are indeed connected together to where I can start the motors with the controller.

So......does anyone know what I'm doing wrong with the firmware update attempts, or have any ideas as to why the camera feed isn't working?  
Please advise if you can.
Thank you
Shawn

  https://youtu.be/3JcHrH1uGYg

Update for clarification:       The problem with me not being able to update the firmware is that no matter what I do, from following the instructions to the letter as well as every other possible combination there is, the two status lights in the very bottom-left of the "Phantom 2 Vision Assistant" software light up at all.  It's as if the computer doesn't see it at all.   I've used multiple cables to rule that out, and the computer does make an audible sound when I plug it in, so the computer sees it, but the software that I need to use to update the drone doesn't.     

Following...

Were you ever able to get the live feed working? I have a Phantom 2 Vision with the same issue.