Basic requirements

  1. Make sure your computer has working adb and fastboot. Setup instructions can be found here.
  2. Enable USB debugging on your device.

Unlocking the bootloader

  1. Download the bootloader unlock app for your device:

    • Navigate to ASUS’ support site and go to your device’s page by entering its model number.
    • Click Driver & Tools.
    • Select Android from the drop-down menu.
    • Open the Utilities section.
    • Download the Unlock Device App.
    • If the downloaded file is packaged in a .zip archive, extract it.
  2. Connect the device to your PC via USB.
  3. On the computer, open a command prompt (on Windows) or terminal (on Linux or macOS) window and change to the location where the Unlock Device App .apk resides.
  4. Install the .apk by typing:
    adb install Name_of_unlock_app.apk
    
    • For example, on the ZE551ML device, it would be adb install UnlockApp_ze551ml_20150723.apk.
  5. Run the application Unlock Device Tool from the device and agree to the terms.

  6. Press the button to unlock your device.
  7. The device should automatically reboot into bootloader mode and the message unlock successfully...reboot after 5 seconds should be displayed. The device will then reboot and load Android.

Installing a custom recovery using fastboot

  1. Download a custom recovery - you can download TWRP. Simply download the latest recovery file, named something like twrp-x.x.x-x-Z008.img.

  2. Connect your device to your PC via USB.
  3. On the computer, open a command prompt (on Windows) or terminal (on Linux or macOS) window, and type:
    adb reboot bootloader
    

    You can also boot into fastboot mode via a key combination:

    • With the device powered off, hold Volume Up + Power.
  4. Once the device is in fastboot mode, verify your PC finds it by typing:
    fastboot devices
    
  5. Flash recovery onto your device:
    fastboot flash recovery twrp-x.x.x-x-Z008.img
    
  6. Now reboot into recovery to verify the installation:
    • With the device powered off, hold Volume Up + Power. On the next screen (fastboot mode) use Volume Down to scroll to “RECOVERY” and then press Power to select.

Installing LineageOS from recovery

  1. Build a LineageOS install package.

    • Optionally, download 3rd party application packages such as Google Apps (use the x86 architecture)
  2. If you aren’t already in recovery, reboot into recovery:
    • With the device powered off, hold Volume Up + Power. On the next screen (fastboot mode) use Volume Down to scroll to “RECOVERY” and then press Power to select.
  3. (Optional, but recommended): Tap the Backup button to create a backup. Make sure the backup is created in the external sdcard or copy it onto your computer as the internal storage will be formatted.
  4. Go back to return to main menu, then tap Wipe.
  5. Now tap Format Data and continue with the formatting process. This will remove encryption as well as delete all files stored on the internal storage.
  6. Return to the previous menu and tap Advanced Wipe.

  7. Select the Cache and System partitions to be wiped and then Swipe to Wipe.

  8. Place the LineageOS .zip package, as well as any other .zip packages on the root of /sdcard:
    • Using adb: adb push filename.zip /sdcard/
    • You can use any method you are comfortable with. adb is universal across all devices, and works both in Android and recovery mode, providing USB debugging is enabled.
  9. Go back to return to main menu, then tap Install.
  10. Navigate to /sdcard, and select the LineageOS .zip package.
  11. Follow the on-screen prompts to install the package.

  12. (Optional): Install any additional packages using the same method.

  13. (Optional): Root the device by installing the LineageOS su add-on (use the x86 package) or using any other method you prefer.
  14. Once installation has finished, return to the main menu, tap Reboot, and then System.

Get assistance

If you have any questions or get stuck on any of the steps, feel free to ask on our subreddit or in #LineageOS on freenode.