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. On the device, dial *#*#7378423#*#* (*#*#SERVICE#*#*) to launch the service menu.
  2. Go to service info > configuration and check rooting status - you can only continue if it says Bootloader unlock allowed: Yes.
  3. Connect the device to your PC via USB.
  4. 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 and connect the USB cable. The notification light should turn blue.
  5. Once the device is in fastboot mode, verify your PC finds it by typing:

     fastboot devices
    
  6. Follow the instructions on Sony’s official unlocking website to unlock your bootloader.
  7. Since the device resets completely, you will need to re-enable USB debugging to continue.

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-tsubasa.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 and connect the USB cable. The notification light should turn blue.
  4. Once the device is in fastboot mode, verify your PC finds it by typing:

     fastboot devices
    
  5. Temporarily flash TWRP to boot:

     fastboot flash boot twrp-x.x.x-x-tsubasa.img
    
  6. Reboot to the TWRP recovery:

     fastboot reboot
    
  7. Push the TWRP image to your device:

     adb push twrp-x.x.x-x-tsubasa.img /sdcard
    
  8. Enter shell on the device:

     adb shell
    
  9. Flash TWRP to recovery permanently:

     dd if=/sdcard/twrp-x.x.x-x-tsubasa.img of=/dev/block/platform/msm_sdcc.1/by-name/FOTAKernel
    
  10. Exit the adb shell:

    exit
    

Installing LineageOS from recovery

  1. Download the LineageOS install package that you’d like to install or build the package yourself.

    • Optionally, download 3rd party application packages such as Google Apps (use the arm architecture)
  2. 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.
  3. If you aren’t already in recovery, reboot into recovery:
    • On boot, press Volume Down when the LEDs start lighting up.
      Second Recovery: To boot the FOTA Recovery, press Volume Up instead.
  4. (Optional, but recommended): Select the Backup button to create a backup.
  5. Select Wipe and then Advanced Wipe.
  6. Select Cache, System and Data partitions to be wiped and then Swipe to Wipe.
  7. Go back to return to main menu, then select Install.
  8. Navigate to /sdcard, and select the LineageOS .zip package.
  9. Follow the on-screen prompts to install the package.
  10. (Optional): Install any additional packages using the same method.
  11. (Optional): Root the device by installing the LineageOS su add-on (use the arm package) or using any other method you prefer.
  12. Once installation has finished, return to the main menu, select 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.