1. Install the ROM Manager on your Samsung Galaxy SII/S2. Get it from Android Marketplace Location, then install the clockwork mod recovery.
2. Connect your Samsung Galaxy SII/S2 to your PC employing the USB information cable. Copy the “Samsung Galaxy SII/S2_4.2 Jelly Bean.zip” file you downloaded to the SD memory card.
3. Restart your device in the recovery mode using ROM Manager. As soon as in Recovery Mode, go to ROM Manager and select backup / restore to back-up your information.
4. From the Recovery Menu do a total data erase (including Delvik Cache). When completed, go back to Recovery Principal Menu and choose Flash ROM from SD Card. Navigate the location you copied the ”Samsung Galaxy SII/S2_4.2 Jelly Bean.zip” file and follow the directions for installing Android 4.2 Jelly Bean on your Samsung Galaxy SII/S2. As soon as the installation is over, just reboot your Samsung Galaxy SII/S2 device, and here you go, you’ve just upgraded it to the new Android 4.2 Jelly Bean. Thank you for visiting Upgrade/Update Samsung Galaxy SII/S2 to Android 4.2 Jelly Bean