Steps

  1. Downgrade the system to update 旧.zip
  2. Root the device with kingroot.
  3. Install busybox and a terminal.
  4. Put unlock_boootloader.sh to /sdcard.
  5. Run busybox.
  6. Run sh /sdcard/unlock_boootloader.sh.
  7. Connect the phone to the computer, and run adb reboot bootloader on computer.
  8. Flash twrp.img to recovery.
  9. Reboot to recovery.
  10. Wipe /cache, /data, and /system.
  11. Push a new system image to /sdcard
  12. Install it and reboot.
  13. Have fun!