Samsung Galaxy S2 is the latest Samsung Galaxy S3 device predecessor. This is not the latest model, but i9100 Galaxy S2 remains one of the best smartphone ever, that’s why Samsung keeps updating the device with the latest official firmware 4.1.2 Android Jelly Bean. One of the best things about this update is that your phone doesn’t need to be rooted and you won’t lose the phone waranty.
This new update brings many new features that make the Galaxy S2 even better and more user friendly. Among these, the best feature is multi-window that allows the user to place on the device’s screen two different tasks and run them simultaneously. A simple example of the ingenuity of this feature is that when listening to music on YouTube, you can navigate on the web, or send a tex message or otherwise. This function can be activated/deactivated by pressing a few seconds the Back button or from the notification bar. Another interesting feature is that you can take a picture while watching a movie or a video from the internal memory using the phone’s video player, by clicking on the camera button at the top of the screen.
Another improvement in this firmware is in Gallery where you can choose how to display the items in 3 modes: Grid and two 3D modes: spiral view and timeline view. You can easily change them from the button on the upper right corner.
How to install:
Step 1. Download I9100XXLSJ_I9100OXXLS1_OXX.zip firmware file and extract it on your desktop
Step 2. Download Odin 1.85 and extract it on your computer
Step 3. Power off your device
Step 4. Start your device in Download Mode by pressing and holding simultaneously Volume Down, Home and Power buttons until the screen lights up and then press Volume Up to continue
Step 5. Open Odin and then connect your SGS2 to your computer using the USB cable
Step 6. Hit the PDA button and select CODE_I9100XXLSJ.tar, hit the PHONE button and select MODEM_I9100XXLS6.tar, hit the CSC button and select CSC_HOME_OXX_I9100OXXLS1.tar and finaly hit the PIT button and select EMMC_EXT4_16GB.pit
Step 7. Make sure you haven’t checked the Flash Lock option and then hit the Start button
Step 8. When the process is finished ODIN should say PASS and your Galaxy S2 will reboot, now you can unplug your phone from the computer
Now you device should reboot the new official firmware with all your old settings.
Source Android Talk