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Update Galaxy S2 GT I9100 to Official Jelly Bean 4.1.2 UHMS9 OS

Samsung had just released a new Jelly Bean 4.1.2 OTA update for the Galaxy S2 GT I9100 for improving the last Android 4.1.2 stock firmware, so if you haven’t received the ROM until now, or if you need to manually install the same, during the present step by step guide we will be checking on how to install the official UHMS9 Android 4.1.2 Jelly Bean software on your Galaxy S2 smartphone.

The UHMS9 Jelly Bean software is the latest update released by Samsung for the Galaxy S2 GT I9100, but don’t expect to receive important changes as this is actually a small improvement that comes to resolve the reported bugs and issues. Therefore by flashing the UHMS9 firmware you will be able to enjoy a more stable version of the Android 4.1.2 OS on your Galaxy S2 while receiving updates for several apps and programs.

Unfortunately, the update can be installed only on the unlocked Galaxy S2 I9100 handsets (except in China, Hong Kong and Taiwan), so this tutorial is not suitable with all the Galaxy S2 models. Furthermore, the Jelly Bean 4.1.2 UHMS9 OS can be OTA or by using KIES applied on your phone, the present step by step guide being dedicated to those who need to manually update their devices.

The manual procedure will be useful for those who own a rooted smartphone as the OTA will not be spotted by devices that have a rooted system. Also, if your phone is currently running on a custom ROM firmware, then completing this tutorial is a must have. Because we are dealing with a stock software, by flashing the same you will not void the warranty of your Galaxy S2. Furthermore, in case the warranty was previously voided, now you will be able to restore it (of course the root access will be revoked and the bootloader relocked).

Anyway, you still have to prepare your device for the update procedure that will follow, so because of that completing the below pre requisites is not an option for you. Take note that for the installation method you will have to use Odin, so make sure that all the tasks from below are being performed or else you will not be able to safely install the official Jelly Bean 4.1.2 UHMS9 ROM on your Samsung Galaxy S2 GT I9100.

  • A Windows running computer or notebook is being required.
  • The smartphone and its USB cord must be near you as well.
  • On both computer and handset you should first deactivate / uninstall all the security tools and settings (turn off the antivirus and Firewall protection too); usually these programs are interfering with the update operation and with Odin.
  • It is recommended to backup the Galaxy S2 data; so save everything you need to (contacts, market apps, EFS and basically everything else) before applying this tutorial.
  • If your phone is installed with a custom recovery image you can also make a Nandroid backup.
  • On your computer download Samsung KIES and install the proper drivers for your S2.
  • Enable the USB debugging option before going any further (go to Settings -> Applications -> Development -> USB debugging).
  • Charge the battery of your device in case there is less than 60% power left; if the device gets turned off while the update process is running, it might get bricked.

Those were the pre requisites. Now your Galaxy S2 has been prepared for the installation procedure meaning that you can safely go and apply the steps from below. Just remember that this tutorial is being suitable only with the Samsung Galaxy S2 model number GT I9100 so don’t perform the same for a similar Android based handset.

How to Update Galaxy S2 GT I9100 to Official Jelly Bean 4.1.2 UHMS9 OS

  1. Download the update file from here.
  2. Also, download Odin.
  3. On the computer extract the update file and install Odin.
  4. Next, open Odin and turn off the phone.
  5. Reboot the Galaxy S2 into download mode.
  6. The download mode can be reached by pressing on the Volume Down, Center and Power buttons at the same time.
  7. With the S2 booted in download mode connect the phone with the computer via USB cable.
  8. Now, take a look on Odin: the ID:COM section should be yellow or blue and the “added” message should be displayed.
  9. If not, you need to close Odin, unplug the USB cable and re-install the drivers on the computer; then repeat the steps.
  10. From Odin select “PDA” and pick the pick the .tar file.
  11. Also, if there are more files on the update package click on: “CSC” and pick the CSC file; on “PHONE” and pick the Modem file; on “PIT” and pick the .pit file.
  12. Up next, click on “Start” and wait while the process is installing the UHMS9 OS on your Galaxy S2.
  13. In the end on Odin the “pass” message will be displayed.
  14. Disconnect the handset from the computer and reboot your phone.
  15. If during the update process Odin gets stuck, you need to: close Odin, unplug USB cable, force restart your S2, re-install the drivers, repeat the procedure from the beginning.
  16. Also, if in the end you will get a boot loop, the you need to: turn off the phone, reboot into recovery mode, select “wipe data factory reset” and “wipe cache partition” and choose “+++go back+++” and “reboot system now”.

Congratulation you have managed to successfully complete the step by step guide meaning that your Samsung Galaxy S2 GT I9100 has been manually updated to official Android 4.1.2 Jelly Bean UHMS9 OS. Test the new firmware and see how it performs; then return here and share your impressions with us and with other users who might want to apply the UHMS9 software.

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