How to Get Uefi firmware on chromebook

TERMINAL GUIDE: MrChromeBox Firmware Utility

To install a custom OS on your Chromebook, you need to interact with the firmware via the command line. This isn't done in a standard browser window; it requires access to the Developer Shell.

Step 1: Accessing the Shell

First, your Chromebook must be in Developer Mode. Once you are at the login screen (or inside your session), you have two ways to get to the terminal:

• Method A (VT2 Terminal): Press Ctrl + Alt + F2 (the Refresh key). Login as chronos.
• Method B (Crosh): Press Ctrl + Alt + T, then type shell and press Enter.

Step 2: The Firmware Command

Once you see the chronos@localhost $ prompt, copy and paste the following command. This script will download the utility and guide you through flashing the UEFI Full ROM or updating your legacy boot options.

cd; curl -LO mrchromebox.tech/firmware-util.sh && sudo bash firmware-util.sh

Important Notes

If you are on a newer version of ChromeOS (R117+), Google has restricted sudo access in the standard crosh window. If the command fails there, you must use the VT2 Terminal (Method A) to run the script successfully.

WARNING: Flashing firmware is a high-level modification. Always ensure your Chromebook is plugged into power and that you have backed up your original firmware to a USB drive when the script prompts you.