If you see that dev mode is blocked, do NOT turn off your Chromebook, it will take you back to register your Chromebook again do NOT go through this process, instead, try pressing esc + refresh + power again.
If you see that dev mode is blocked, do NOT turn off your Chromebook, it will take you back to register your Chromebook again do NOT go through this process, instead, try pressing esc + refresh + power again.