A quick browse around to the Android Authority website will let you know that there are just certain devices that developers are in love with. In fact, whenever a new update comes out, those devices are always the first to receive leaks, ports and stable custom ROMs. The Samsung Galaxy S2 GT-I9100G, the more up-to-date variant of the popular Galaxy S2 GT-I9100, is definitely one of the apples of developers' eyes and is getting another injection of Android 4.1.1 Jelly Bean.

The Codename Android custom ROM, developed by XDA Developers member samyam2002000 and based off of Clean Android 4.1.1 Rev4, comes with a bunch of neat features. It has a File Manager baked into it, the T-Mobile Theme Manager, and the Trebuchet Custom Launcher. You can also set a custom ringtone delay. That isn't all there is in this custom ROM, of course.  There are more.  That's why you might want to load up your phone with it.

This guide shows you how to upgrade the Galaxy S2 I9100G to Android 4.1.1 Jelly Bean via Codename Android ROM.

Warning

• The instructions in this guide are intended for use with the, Samsung Galaxy S2, model number GT-I9100G. 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

• Samsung Galaxy S2 GT-I9100G with ClockworkMod Recovery installed and running Android 4.0 Ice Cream Sandwich XXLPQ firmware.
  • Check out this guide on how to flash the XXLPQ firmware and how to root and flash ClockworkMod Recovery to your Samsung Galaxy S2 GT-I9100G running the XXLPQ firmware.
• Download the following files to your computer:
  • Codename Android 3.4.1 ROM (codenameandroid-3.4.1-i9100g.zip, 128.62 MB).
  • Google Apps package (gapps-jb-20120726-signed.zip, md5sum: f62cfe4a827202899919fd932d5246d7).
• Make sure your device's battery still has at least 70% power. You don't want the device to shut down in the middle of the procedure.
• 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.
  • For backup tips, check our guides on how to sync your data to the cloud and how to create local backups of your mobile data.

Instructions

1. Copy both the ROM file and the Google Apps package to your Galaxy S2′s internal SD card.
2. Turn off your Galaxy S2.
3. Boot into Recovery Mode. You can do this by pressing and holding down the Volume Up, Home, and Power buttons until recovery boots.
4. Make a NANDroid backup by selecting Backup and Restore. Select Backup.
5. Select Wipe data/factory reset. Confirm the action on the next screen.
6. Select Install ZIP from SD card. Select Choose ZIP from SD card and select the Codename Android ROM.
7. Once the Codename Android ROM has been installed, repeat step 6 and this time, select the Google Apps package.
8. After the Google Apps package has been installed, select Go back.
9. Select Wipe data/factory reset. Confirm the action on the next screen.
10. Select Reboot system now.

Congratulations! You've just given your Samsung Galaxy S2 GT-I9100G a dose of Android 4.1.1 Jelly Bean through the Codename Android ROM.