Restore back Acer C720 Chromebook to Factory Reset state (Rollback Write Protect disable and Linux Installation hacks!)



After playing with my Acer C720 Chromebook as detailed in my previous post – Installing Ubuntu on Acer C720 Chromebook and dual boot with Chrome OS – now it is time to restore back everything to bring the Chromebook to Factory Reset state. Only thing you can’t restore back is “Your Warranty” 🙂

It involves following steps.

  1. Prepare Chromebook Recovery USB media or keep the one you have already done ready.
  2. Ensure that Write Protect is disabled. Program the Flash ROM with configuration reset.
  3. Recover the Chromebook.
  4. Enable the Write Protect again.

Chromebook Recovery USB:

Here we are going to follow this guide on preparing Recovery USB drive, so that it will be useful to revert back everything normal in case something goes wrong during this hack work.

  1. Install Chromebook Recovery Utility from Chrome Web Store on your Chromebook.
  2. Insert USB drive or SD card of minimum 4GB on Chromebook.
  3. Run the installed application and follow the instructions to prepare this recovery drive.

In case of you have Linux PC the above mentioned method does not work. You may follow my another post on getting it done through a Linux PC.

Disable BIOS Write Protect:

Write Protect Screw on Acer C720

Write Protect Screw on Acer C720

  1. Remove all screws on bottom of Acer C720 Chromebook including the one under warranty sticker. Be warned that this will end up losing warranty of this Chromebook.
  2. Remove the Write Protect Screw on PCB as shown by the picture above. Keep this screw safe. Note: You can place this screw back to this space again after programming the Flash ROM with modified settings as shown in next section.
  3. Place the cover back and screw them firmly.

Recover Chrome OS with Recovery Media:

  1. Press and hold the Esc + Refresh keys.
  2. Press the Power button, then let go.
  3. Continue holding the Esc + Refresh keys until the “Chrome OS is missing or damaged” message appears, then let go.
  4. Plug in Recovery Media we prepared.
  5. It should automatically detect the Recovery media and start recovering. Hey! Now you have Fresh Chrome OS installation wizard!

Enable BIOS Write Protect:

Program the flags to restore default.

  1. Boot the Chromebook – On Chrome OS screen, press Ctrl + Alt + -> keys to get root shell.
  2. Login as user “chronos” without password.
  3. Run “sudo /usr/share/vboot/bin/set_gbb_flags.sh 0x0
  4. Run “sudo reboot” to reboot the Chromebook or Shutdown.

Now enable the BIOS Write Protect with screw:

  1. Remove all screws on bottom of Acer C720 Chromebook including the one under warranty sticker. Be warned that this will end up losing warranty of this Chromebook.
  2. Place the Write Protect Screw on PCB as shown by the picture above.
  3. Place the cover back and screw them firmly.

 



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