chromebook turn on developer mode
1. Turn on your Chromebook.
2. Press and hold the Esc key, refresh key, and the power button at the same time.
3. Press and hold the Ctrl and D keys at the same time. (When the “Chrome OS is missing or damaged. Please insert USB stick.” message shows up)
4. Press Enter (if required).
5. Press Ctrl and D to restart successfully. ( You will get an odd screen saying that OS verification is off. Keep in mind this screen will happen every single time you boot up.)