Create recovery media for your Chromebook.
How to Create a Chrome OS Recovery USB Drive
How to create a Chrome OS Flex USB installer - iFixit Repair Guide
How to Create a Chrome OS Recovery USB Drive
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How to fix 'ChromeOS is Missing or Damaged' on your Chromebook
How to Create a Bootable USB on Chromebook
How to install ChromeOS Flex on an old laptop
How to Use the Chromebook Recovery Utility to Create Recovery Media
How to revert Chrome OS to a prior version on a Chromebook
How to Turn Your Old Mac into a Chromebook - MacRumors
My Chrome Home: Download and recover Chromebook Recovery Image Directly without Recovery utility (Updated Nov 2015)