Here’s the manner How to manually update your Nexus.
- Go to your Nexus’ Settings and scroll down to About Phone/Tablet.
- Tap on the Build number seven times until the dialog box says you are now a developer.
- Go back to the Settings menu and you should find a new option called Developer options.
- Make sure that the developer options are turned on and that USB debugging is checked on.
- If you’re upgrading a device running Lollipop or higher, make sure Enable OEM unlock is checked.
- Plug your Nexus device into your computer and click “ok” on the dialog box asking you to Allow USB debugging while connected to the computer. You can also select to always allow access on that computer.