How to Install Android 4.3.1 Jelly Bean in Samsung Galaxy S2 I9100.

Tools Requirements:-
1. Charging Your battery up 80%.
2. Make sure that you have enabled USB debugging.
    (All Apps---> Setting--->Manage Application---> Development--> USB Debugging-->Check box)
3. The Tablet must be rooted and  CWM recovery Installed.
Must Read:- How to Install CWM Recovery in Samsung Galaxy S2 i9100.
Must Read:- How to Root Samsung Galaxy S2 i9100.
4. Backup to your all important data.
5. Download Android 4.3.1 CarbonRom 1.9.1 :- Click Here to Download

Method to Install CarbonRom 1.9.1 Custom Rom for Samsung Galaxy S2 i9100.
1. Download CarbonRom 1.9.1 custom Rom in your Computer and paste in your External SD Card.
2. Switch Off your Tablet.
3. Press Volume Up + Power button + Home button then go to "CWM recovery mode"
5. Then go to backup & restore -----> backup (wait 15 to 20 minits)
6. Select “Wipe Data/Factory Reset”, this will clear all previous ROM data and your
    applications.--->yes
7. Select "Wipe Cache Partition"----->Yes
8. Then Select "Wipe Dalvik Cache" ---->Yes
9. Then go to Install Zip from sdcard.---->Choose zip from sdcard.---->Select Zip file to sdcard.
10. Select Yes and the Installation will Start.
11. Reboot phone after installation is Complete.
      Congratulation

The phone will take 10-15 minutes to start and initialize all the services & apps because this is the first time you are starting a phone after installing ROM. Don’t be hesitate and wait for complete process.

Enjoy Your Samsung galaxy S2 i9100 Successfully Install Carbon Custom Rom. 
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Note:- I am not responsible if you make any mistake and damage or any other problem your device.