Ensure that you have a WiFi connection; this is required for downloading the SeaBIOS extension.
Boot into recovery mode by pressing ESC + (Refresh) + (Power) simultaneously.
The recovery mode screen is shown, which states that the OS is broken.
Press Ctrl + D to enter developer mode.
The developer mode screen is shown, confirming that OS verification is off.
Open a root-capable shell by pressing Ctrl + Alt + (F2).
Login as chronos; no password is required unless one has been set.
Change to /tmp: cd /tmp.
Download the ChromeOS firmware utility script: curl -LO https://mrchromebox.tech/firmware-util.sh
Start the script with root permissions: sudo bash firmware-util.sh
Enter 1 to select the first option.
Enter y to confirm.
The RW_Legacy firmware is downloaded to your device.
When the download has completed, press Enter.
Enter r to reboot.
The device reboots into developer mode.
To boot from UD Pocket, press Ctrl + L.
Booting from UD Pocket
Ensure that the device is in developer mode. This should be the case if the device has been configured according to the procedures described above, and if since then no changes were made that have affected the developer mode.