sudo crossystem dev_boot_legacy=1
crossystem disable_dev_request=1; reboot
from a root shell. There's no way to enter Dev-mode programmatically, and just seeing the Recovery screen isn't enough - you have to use the three-finger salute which hard-resets the machine first. That's to prevent a remote attacker from tricking your machine into dev-mode without your knowledge.# chromeos-firmwareupdate --sb_extract /tmp
# flashrom -w /tmp/bios.bin -i RW_LEGACY
firmware-panther-4920.24.B
branches.