Samsung Galaxy S2 I9100 users who have already updated their devices with Android 4.1.2 Jelly Bean, may root their devices using the tutorial below.
Disclaimer: Rooting voids the warranty of your device. We and the developer of this rooting procedures shall not be held responsible if any undesirable outcomes may happen to your device. use of this root guide is solely at your own risk!
1) Install USB Driver for Samsung Galaxy S2 on the computer.
2) Enable USB Debugging Mode on the phone.
3) Make a backup of all your important data before following the guide.
4) The Galaxy S2 should be factory unlocked and not locked to any particular carrier.
5) Ensure the battery of the phone is charged more than 80 per cent.
6) The Root Kernel file works only on Samsung Galaxy S2 I9100 running on Android 4.1.2 Jelly Bean firmware. Applying this on any incorrect variant will brick the device. Verify the model number of the Galaxy S2 by navigating to Settings >> About Phone.
1. Root Kernel for Galaxy S2 I9100: Siyah-s2-v6.0b4.tar or Siyah-s2-v6.0b5.tar
2. Odin 3.07
Steps to Root Galaxy S2 I9100 Running on Android 4.1.2 Jelly Bean Firmware
Step 1: Extract Odin 3.07 file using winrar/7zip/winzip or any other extracting tool.
Step 2: Switch off the Galaxy S2. Then boot the device into Download Mode by pressing and holding Volume Down + Home buttons together and then press the Power button until the device turns on. Now press the Volume Up button to enter Download Mode.
Step 3: Launch Odin on the computer.
Step 4: Connect the Galaxy S2 to the computer using USB cable while it is in the Download Mode. Wait until Odin detects the device. When the device is connected successfully, the ID: COM box will turn yellow with the COM port number. Additionally, the successful connected will be indicated by a message saying Added. If Odin fails to detect the device then re-install USB driver.
Step 5: In Odin, click the PDA button and select the Root Kernel file.
Step 6: Verify that Auto Reboot and F.Reset Time checkboxes are selected in Odin. Also, ensure the Re-Partition option in Odin is not selected.
Step 7: Double-check and click Start in Odin. The installation process will now begin.
Step 8: Once flashing completed, your phone will restart and soon you will see a PASS message with green background in the left-most box at the very top of the Odin. You can now unplug the USB cable to disconnect your device from computer.
Samsung Galaxy S2 I9100 running on Android 4.1.2 Jelly Bean firmware is now rooted successfully. You may now install any app that requires root permission.
Thank's to all fellas at XDA who first tried out this rooting technique. This root method was originally posted via XDA-Developers.