Aqui teneis la informacion de primera mano:
https://developers.google.com/android/ota
To apply an OTA update image:
1. Make sure that there is no pending OTA update, by going to Settings > About phone > System updates, which should say "Your system is up to date".
2. Download the appropriate update image for your device below.
3. Verify the checksum of the image: the OTA mechanism has a built-in validation feature, but verifying will save you some time if the file is incomplete. The last portion of the filename is the first 8 digits of its SHA-256 checksum; the full SHA-256 checksum is also shown next to the download link.
4. With the device powered on and USB debugging enabled, execute:
adb reboot recovery
If you're unable to use adb to reboot into recovery, you can use the key combination for your device instead, and then select the Recovery option from the bootloader menu. The device is now in recovery mode and an Android logo with red exclamation mark should appear on screen.
5. Hold the Power button and press Volume Up once, and a menu will appear. Select the option Apply update from ADB.
6. Run the following command:
adb devices
and check that your device shows up with "sideload" next to its name.
7. Run the following command:
adb sideload ota_file.zip
where ota_file.zip is the name of the file you have downloaded and verified.
8. Once the update finishes, reboot the phone by choosing Reboot system now.