specific to HP..
The
HP Chromebook 14 comes with
Coreboot, a Free Software BIOS replacement, preinstalled.
1 For security reasons the factory default settings of Coreboot allow you to run Google-signed images only. To install Debian (or any other non-Google-signed OS) you have to put your Chromebook into developer mode and enable
boot from USB and
boot legacy OSes first.
Enter developer mode
1. Backup all local user data! When you enter developer mode all data will be lost.
2. Enter recovery mode by holding down ESC+Refresh and hitting the power button.
3. In recovery mode, press Ctrl+D. You'll get the message
To turn OS verification OFF, press ENTER. Your system will reboot and local data will be cleared – hit Enter and wait. After a few minutes your Chromebook will boot into developer mode.