Galaxy S2 I9100 can be updated to Android 4.2.2 Jelly Bean via Omega ROM. Omega ROM for Galaxy S2 I9100 is based on AOKP Team & CM Team sources. This is a Custom ROM and not an official ROM update from Samsung.
The guide mentioned below is only for Galaxy S2 I9100 and cannot be tried on any other device or variant. You can check device model by going to Settings >> About phone.
We cannot be held liable of any damage done to your device while following the below mentioned procedure.
Install Android 4.2.2 Jelly Bean Omega ROM on Galaxy S2 I9100
Take a complete backup of data,apps and settings as the procedure may wipe your data.
Make sure that the battery of device has a minimum charge of 60%.
Enable “USB debugging” on your device by going to Settings >> Developer options >> Enable USB debugging.
ClockworkMod Recovery should be installed. Guide to install ClockworkMod Recovery on Galaxy S 2 I9100.
Download the latest version of ROM from source page here.
Extract the zip file to SD-card of your device without extracting.
Switch off device and boot into recovery. Hold power button and volume down button and enter recovery.
Perform a Nandrop backup of your existing ROM. Select “Backup and Restore” and then select “Backup again”.
Select “wipe data/factory reset” and wait till the data gets wiped completely. Click on “Advanced” and wipe off Dalvik cache.
Select “install zip from sdcard” and then select “choose zip from sdcard”. Navigate to “Omega ROM” file which you have downloaded and confirm to “install”. Wait till it gets installed.
Select “reboot system now”.
You have installed Omega ROM based on Android 4.2.2 on Galaxy S2 I9100.