STEP BY STEP GUIDE:
How to update the Sony Xperia S to Android 4.0 Ice Cream Sandwich


1: This guide is for WINDOWS PC USERS, if you have a Mac I can't help you, but the process is very similar

2: It doesn't matter if your phone is rooted or not, bootloader unlocked or not, IT DOESN'T MATTER, this update has nothing to do with SIM unlock, bootloader lock / unlock, root, etc

3: This guide will update your Xperia S from ANY previous version to OFFICIAL SONY ICS ANDROID 4.0.4 and believe me: it is worth the update; HAT TIP TO SONY !!

4: The internal SD card contents will NOT be deleted but everything else inside your phone will be reseted to factory defaults because this is a major update, so do a backup if you want to keep call logs, SMS etc. I only backup my SMS and Whatsapp messages, google backed up everything else because I had the backup option activated in settings

5: Before asking, please read the questions and answers in the thread for many Frequently Asked Questions


STEP 1:
Download the Flashtool
You will find the installers here: Flashtool - Xperia devices flashing
Go to the "installation" tab, download Flashtool installer v0.9.10.1 and run it
You will have a new folder on your PC: c:\Flashtool

STEP 2:
Download the ICS firmware update

You will find several download options here:
https://docs.google.com/open?id=0Bx5...EJBQTNtb0wxWkk
http://forum.friendsgsm.com/vbb/f949...on-all-devices

just pick one and download it, then come back here

STEP 3:
Let's update the phone!

- Copy the firmware FTF file to c:\Flashtool\Firmwares
- Go to c:\Flashtool\Drivers and run "Flashtool-drivers.exe" to install the proper drivers for Xperia S
- After installing the USB drivers reboot your PC
- Go to c:\Flashtool and run "FlashTool" (if you have Windows 64 bits, run "FlashTool64")
- Click the flash button (yes: the thunder icon up left)
- Select "Flahsmode" and click "OK"
- Select the "LT26 6.1.A.0.452" firmware and click "OK", DON'T TOUCH ANYTHING ELSE
- Flashtool will prepare the files for flashing, just be patient
- A Window will pop up asking you to connect the phone in "Flashmode" showing instructions for an old Xperia phone: ignore it, here is how the Xperia S enters "Flashmode":

- Turn off the phone
- Press and hold the VOLUME DOWN key
- Keep it pressed, connect the USB cable to your PC
- Release the Volume Down key when phone's GREEN LED lights up
- Flashtool will start flashing automatically, let it finish to 100%

- Disconnect the USB cable when Flashtool reaches 100% and indicates flashing has finished giving some extra info about activating debugging mode etc (don't care, that's optional)
- Turn on your phone (press and hold the Power button for some seconds)
- The first boot takes some minutes, don't worry let your phone prepare your Ice Cream Sandwich for you
- Have fun !!