I need to revert my Samsung Chromebook 4 (bluebird) to stock chromeos, however the backup bin that I needed to flash was lost. Does MrChromebox utility script have a way of reverting back without the backup or am I stuck? I saw a post about this exact topic and I'm not really sure what they were talking about.

If it's any consolation, I do have the vpd backed up from the mrchromebox uefi firmware.

here's the post I was talking about:
https://www.reddit.com/r/chromeos/comments/16fspjv/where_can_i_get_the_firmware_backup_for/

  • parent

    Disconnecting the battery to disable WP is giving me a flashing red light when trying to power the device on with a charger.

    parent root

    It may depend on your device type but I believe I'm right in saying that for devices that disable WP by disconnecting battery, after the initial battery disconnect reconnecting battery does not re-enable WP. You should therefore be able to restore stock firmware with the battery connected. Of course, MrChromebox is the authority on this, but since you omitted your HWID I wouldn't expect a response.

    parent root

    Thank you, I updated the post to include the model. However when I do run the MrChromebox script it says write protection is enabled and won't let me do any steps that require it to be disabled.

    parent root
  • parent

    Does MrChromebox utility script have a way of reverting back without the backup or am I stuck?

    is the documentation on my site unclear on this?

    parent root

    No, I see that you can restore from a downloadable recovery image, however I'm having a new issue where I'm unable to disable write protect (disconnect battery) without the chromebook flashing red led when plugged in.

    And like the other comment said, once it is disabled, it stays disabled, is this accurate?

    parent root

    And like the other comment said, once it is disabled, it stays disabled, is this accurate?

    semi.

    if you used my script to flash the firmware originally, then it disabled software WP (flash chip registers), which is what the script checks for. The hardware WP (screw, jumper, CR50, battery etc) just prevents you from changing the SW WP on the flash registers. But if those are cleared/disabled, then the state of the HW WP is irrelevant.

    Exit the script, and run: sudo /tmp/flashrom --wp-status and copy/paste the full output here

    parent root

    /tmp/flashrom: command not found

    Also I used a ch341a programmer to flash your firmware directly to the bios chip not your script.

    parent root

    Also I used a ch341a programmer to flash your firmware directly to the bios chip not your script.

    that's your problem then, you never disabled software WP. You need to use the ch341a to disable it:
    sudo flashrom -p ch341a_spi --wp-disable
    sudo flashrom -p ch341a_spi --wp-range 0,0

    then you can use the script on the device to go back to stock

    parent root

    This worked thank you so much, and how would I re-enable fw wp afterwards?

    parent root

    sudo flashrom -p ch341a_spi --wp-region WP_RO
    sudo flashrom -p ch341a_spi --wp-enable

    though you can do this from ChromeOS dev mode using flashrom and the internal programmer as well. But be sure to clear the GBB flags and set a valid HWID before doing so, if they are not valid/correct after restoring the stock firmware via recovery.

    parent root
    parent root

    run my script from ChromeOS, and:

    • set the GBB flags to default
    • set a valid HWID for your device. use: BLUEBIRD C4B-A2D-C3Q-G3U-A2F

    then reboot, make sure everything is good, then set the WP stuff as per above from ChromeOS, then exit Dev mode

    parent root