We have had the same problem with Netflix not working. The steps we have taken are as follows: (Note, purchased this Apple TV HD from Costco.
- Deleted Netflix and then reinstalled the app and it "FAILED" to launch
- Restarted the apple tv and then removed Netflix and reinstalled the app and it "FAILED" to launch
- Tried to update the software for the Apple TV from the menu. - Selected "download update", allowed the process to complete the download, watched the 1st and 2nd step parts of the install and..... it "FAILED" to update to any new software. Then I repeated the process just incase I made an error which produced the same result. Software update "FAILED" to install.
- As a final measure, I reset the Apple TV HD to it's factory settings and erased everything. I also discovered that the Apple TV would not sync to my phone under standard setup as instructed so I selected manual setup. I entered my Apple ID and Password, connected to our network, allowed the Apple TV HD to perform the standard setup as if it was new out of the box and ..... surprise, surprise.... Netflix still "FAILED" to launch.
In review, I have attempted every step including contacting Netflix who says this is an APPLE problem. So short of learning C++ and doing a full blown hack of the little black HD demon, I am out of answers or solutions.