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How to Manually Install Official Samsung Galaxy S2 GT-I9100 Android 4.1.2 Jelly Bean Update

Samsung reportedly started rolling out the much anticipated Android 4.1.2 Jelly Bean update with build JZO54K for the Samsung Galaxy S2 GT-I9100 today. In a report published by Sam Mobile, it is shown that the roll out started in Spain. It is expected that other regions including the U.S. and the rest of Europe will receive the same update in the following days or weeks. However, users who may not be able to sit tight and wait for the official rollout may now update their device manually, although there are some risks involved.

We have prepared a step-by-step guide for you to follow. This will walk you through successfully installing official Android 4.1.2 Jelly Bean I9100XWLS8 on your Galaxy S2 with model number GT-I9100. Be sure to check reminders and requirements we prepared to help you with the flashing of this ROM.

Official Firmware Details

Android Version: 4.1.2 – Build JZO54K




Changelist: 816988

Build Date: 14 January 2013


  • The Android 4.1.2 JB update with build JZO54K is intended for Galaxy S2 model GT-I9100 only. Make sure you check the model number by going to Settings => About phone before you decide to follow the steps below. Please be advised that flashing this ROM to other models may brick your device.
  • You should backup all your important data so you can always retain them in case bad things happen during the flashing.
  • It is recommended you fully-charge your phone before the process, or leave, at least, 80% battery.
  • Make sure you have installed all necessary driver so your phone can be detected properly by your computer.
  • Since it is an official build, all access to custom ROMs including CyanogenMod and AOKP will be lost after the installation.
  • You will also lose root access and ClockworkMod Recovery tool will be uninstalled.


  1. Your phone should be rooted because manual installation of ROMs, even if they are official builds, requires root access.
  2. The ClockworkMod Recovery tool should have already been installed in your device. If you haven’t done so, you must at this stage.
  3. Enable USB Debugging.
  4. You must download and extract these files: Android 4.1.2 Jelly Bean I9100XWLS8 and Odin application.


Step 1: Go to the directory where you have extracted contents of Odin package you have downloaded a while back. There should a single file in there, right-click on it and choose “Run as Administrator” option.

Step 2: Turn your Samsung Galaxy S2 off and boot it into Download Mode. Press and hold POWER DOWN and HOME buttons while tapping on the POWER button until Samsung logo appears on the screen.

Step 3: Using the original USB data cable, connect your phone to the computer. If there is a good connection established between them, one of ID:COM boxes on Odin UI turn yellow. Otherwise, try a different USB port until you establish a good connection. This step could be time-consuming and sometime it would boil down to reinstallation of USB drivers.

Step 4: You must first check if there is a “.pit” file that comes with the official Jelly  Bean package. So, navigate through the directory where you’ve extracted the files. If you can find the pit file, load it. Otherwise, just close the window and proceed to next step.

Step 5: Under the “Option” section on Odin UI, check options Auto Reboot and F. Reset Time. Assuming there is a pit file that comes with this package, you are required to check Re-Partition option, too. Otherwise, leave it unchecked.

Step 6: Click PDA button and load the “.tar.md5” file from the same directory you extracted contents of the official firmware.

Step 7: Click PHONE button and load ‘MODEM’ file.

Step 8: Click CSC button and find file with ‘CSC’ in its file name and load it.

Step 9: Assuming you have loaded all files correctly (and have double-checked it), you are ready to begin flashing. Click on START button.

Step 10: Wait and never interrupt while the flashing process is underway. Wait until Odin displays “Pass” message and your phone was automatically rebooted before you disconnect it from the computer and use it.

To verify if the installation was successful, go to Settings => About phone. You should see Android 4.1.2 as the OS and JZO54K as its build.

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