No, unlock is not required, at least not according to the instructions there. So stock recovery should be sufficient.
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These are full images, not incremental files. Boot into recovery and use ADB sideload to push the update over from your computer. You won't need an unlocked bootloader as you would for a factory image. It will not wipe your data, but you should back up just to be safe.


Edited by mlord (23/08/2016 01:25)