[Chromebook] Troubleshooting - Chrome OS is missing or damaged

If you experience that the Chromebook does not start and displays the message of “Chrome OS is missing or damaged”.

 

Please insert a recovery USB stick or SD card into the Chromebook, learn more about How to recover Chromebook operating system.


Above contents are from Google official website, you can also refer to Google Help Center for more details. 
If your problem is not worked out with above solution and information, please contact ASUS customer service center for further information.