I recently updated the firmware on my phantom three standard and now it will not connect the remote to the drone. I have scoured the Internet and have found the secret back door in the upper right-hand corner of the DJI go app. My current firmware says unknown and also says device not connected. I am trying to install a new version of the firmware but cannot find any instruction or tutorial on how to do that. Any help would be greatly appreciated.

What happens when you power up the app, RC, and aircraft? what lights are on the RC and aircraft?
In the about page of the general settings, what do you see?