Upgrade the Galaxy S2 I9100 to Android 4.1.1 Jelly Bean build JRO03H from AOSP sources

As of the moment, there is no official Jelly Bean update for the Samsung Galaxy S2. Custom ROMs based on the new Android 4.1 Jelly Bean are still spreading like wildfire to different Android developer communities. Currently, custom ROM developers, like CyanogenMod and AOKP, have fashioned decent custom ROMs based on Android 4.1. These ROM developers added custom features but still provide a pure Android experience like the one you can find on Google’s Nexus devices.
Galaxy S2 users can’t wait to install this fastest and smoothest version of Android on their Android devices.
XDA Developers member cile381 crafted a Jelly Bean ROM for the Galaxy S2 based on build JRO03H Android 4.1.1 without modifications or bloats. This ROM was compiled from stock AOSP source code. This custom ROM is faster and smoother with all the new features of Android 4.1. The experience of moving between home screens and switching between apps can be yours, like turning pages on a book.
The ROM is in its early phase, so bugs and issues may be present. The ROM is not recommended for day-to-day use but can provide you a sneak preview of Android 4.1.1 Jelly Bean on your Galaxy S2 I9100.
In this guide, learn how to upgrade the Galaxy S2 I9100 to Android 4.1.1 Jelly Bean build JRO03H from AOSP sources.

Warning

• The instructions in this guide are intended for use with the Samsung Galaxy S2, model number GT-I9100. Applying these instructions on another device or model may produce undesired outcomes.
• The information in this guide is provided for instructional and educational purposes only. There is no guarantee that these instructions will work under your specific and unique circumstances.
• Use these instructions at your own risk. We shall not hold any responsibility or liability for whatever happens to you or your device arising from your use of the info in this guide.
• Read and understand the whole guide first before actually performing the instructions.

Requirements

• Download the AOSP JB 4.1.1 ROM (Jellybean 4.1.1-SGS2-Intact-AOSP-V1.2.zip, md5sum: f0cce39892561f6a1d2864dd399ed11b)
  • Direct Link
  • Mirror Link
• Download the GApps (Google Apps) Package (gapps-jb-20120726-signed.zip, md5sum: f62cfe4a827202899919fd932d5246d7).
• Backup all personal data on your phone to make sure you have a copy of your personal data (e.g., contacts, SMS, MMS, Internet settings, Wi-Fi passwords, and the like) in case the procedure in this guide erases such data.

Instructions

1. Copy the AOSP JB 4.1.1 ROM ZIP file and the GApps package to the phone’s internal SD card.
2. Turn off your Samsung Galaxy S2.
3. Reboot your Samsung Galaxy S2 into ClockworkMod Recovery Mode. You can do that by pressing and holding down the Volume Up key, Home button (middle key), and Power button simultaneously until recovery boots.
   • NOTE: Once in ClockworkMod Recovery Mode, use the Volume keys to navigate and the Power button to select an option.
4. Create a NANDroid backup of your current ROM. Go to Backup and Restore then select Backup on the next screen.
5. Go back to main menu and perform a full wipe:
   • Select Wipe data/factory reset and confirm the action on the next screen.
   • Select Wipe cache partition and confirm the action on the next screen.
   • Go back to the main menu and select Advanced. From there, select Wipe Dalvik cache and confirm the action on the next screen.
6. Return to the main menu and select Install ZIP from SD card.
7. Select Choose ZIP from SD card and locate the ROM ZIP file. Confirm the action on the next screen to start installing the ROM on your Samsung Galaxy S2.
8. Once the installation is complete, go back and select Reboot system now to restart your phone.

Hooray! You have successfully installed the AOSP-based Android 4.1.1 Jelly Bean build JRO03H on your Samsung Galaxy S2 GT-I9100.