Xperia TL comes with locked bootloaders, and the bad news is our AT&T branded phone is not supported by the official Sony unlock program, only the international devices are supported by this program. So we will not be able to run custom ROMs especially AOSP or CyanogenMod ROMs.
However, although it is still locked, we can still install a custom recovery which is very useful to carry out a full ROM backup, wipe data/cache partition, flash stock ROM, etcetera. Thanks to davidmarco from Xda, who provide a way to install CWM recovery on the Xperia TL (LT30at) with locked bootloader. He has built a custom script that is able to put in CWM easily, so it is basically a one-click solution.
Listed below are the prerequisite and the steps that you should undertake to set up CWM recovery on Xperia TL, tested on devices with build number 7.0.B.1.152 (Ice Cream Sandwich firmware).
- Root your devices, you can read the complete guide here, your phone must be on stock ICS (Android 4.0) in order to be rooted, due to the fact that until now there is no root method for Jelly Bean firmware.
- Make sure your TL Xperia identified by your PC, you need to set up the device drivers by using PC Companion.
- On your phone enable USB debugging feature in Settings > Developers.
- Connect your phone to the PC via USB cable.
- Grab CWM 4 installer for Xperia TL by davidmarco, be sure you download the ICS version.
- Extract or unzip the file anywhere on your PC/Notebook.
- Open the folder and run install.bat, cmd window will appear and the CWM recovery installation will begin.
- Now you should have CWM recovery installed.
To get into recovery mode, turn off your phone, then switch it on, note when the Sony logo appears, press volume down key repeatedly (not just holding it) until the phone vibrates. Makes use of the volume buttons to move between menu and power button to select menu.