How To Unlock, Relock Sony Xperia T LT30 Bootloader

How to unlock and relocked Sony Xperia T LT30 bootloader? This is now more easier.  We can easily do it with the fastboot and flashtool. There are many reasons for unlocking the bootloader, primary reason is install a custom kernel, recovery. The major reason for relock the bootloader, is claim the warranty or use the OTA update.

If you need to unlock the bootloader, you can follow my how to unlock Sony Xperia phone bootloader tutorial. All the devices have the same method. But relocking rather different, because of we have to install a ftf file in that situation.

After you have installed this ftf file, you have to install the new firmware using flashtool.  Otherwise your phone will not boot.



This tutorial contains ftf file only for the Sony Xperia T LT30. If your phone brick or damaged by following this tutorial, I can’t claim its damages. Applying that file to another device, may brick your phone.



  • Sony Xperia T bootloader relock file in here.
  • Android 4.0.4 firmware in here or Android 4.1.2 firmware in here. (If you already have no need to download/ no need to download both file, get only one)
  • Flashtool application in here. (You can use jDownloader, Link Grabber for easily download files)


How to relock Sony Xperia T LT30.

This method first we install the relocking file after that we have to install any Xperia T firmware.  It’s highly recommend to install your region or carrier based version.

  • Install the Flashtool computer application.
  • Copy the downloaded relock and desire firmware ftf file into the flashtool installed directory contain “Firmware” folder.
  • Disconnect phone from the PC and power off.
  • Run the flashtool.
  • Click the top “Thunder” icon, like the following screenshot.


  • Mode selector window, make sure that “Flash mode” ticked.
  • Next “Firmware Selection” window, choose the “Bootloader Relock” file.
  • To start the installation, click “OK”.


  • Make sure that your phone fully power off.
  • Now press and hold the Volume Down key and at the same time connect Xperia T to the PC via USB cable.
  • When you see the popup window and promote to disconnect phone from the PC, wait for a few seconds. Don’t disconnect your phone.
  • After the relock file installation completed, again install the downloaded firmware just like you installed the relock file. ( Start from 5th step, or follow my how to update Xperia T to jelly bean tutorial)


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