From a Home screen, touch and swipe up to display all apps.
Navigate: Settings > System > Advanced.
Tap System update .
From the System update history prompt, tap Check for update.
If prompted, tap OK.
If an update is available, tap Download.
If prompted with 'Your system is up to date', no update is necessary.
If the device gets stuck in the boot-up process after installing an update, a factory data reset is required. Make sure the Google credentials are known prior to doing the reset as they are required to complete the reset process.