How to upgrade Android on Nesus 6 after it`s downgrade I have an Nexus 6 phone in my company which is used for automatic testing purposes. After release of Android 6.X our framework was not ready to work with new permission system so we downgraded Nexus 6 to Android 5.X official images.

Now we have deal with permission problem and now want to make Nexus 6 run on Android 6, but inside menu Setting -> About Phone -> System Update there is no available updates. What is the best way to install Android 6 with ability to automatically be informed when new updates will be released (6.+ and android 7.+)
The best way would be to manually flash the Google factory images to get to Android 6.0.1, then all the monthly security updates will come via OTA, and when 7.0 comes out, eventually the phone would get that as well.

Google Nexus Factory Images