Android 4.2.1 update
CyanogenMod 10.1 with Android 4.2.1 ROM released for Galaxy S2 I9100. XDA Developer

XDA developer codeworkx has followed the release of CyanogenMod 10.1 (CM10.1) custom firmware for the Samsung Galaxy S2 (I9100G), with a file for the I9100 version of the S2. The unofficial firmware offers Android 4.2.1 (Jelly Bean) but there are bugs in this build, meaning users are advised not to create ROMs based on the software. Known issues include problems with the User Interface (UI), audio and camera. For more details, visit the development page.

Galaxy S2 users looking to update with this build may follow this guide. IBTimes UK reminds its readers it will not be responsible for damage to the device during installation and that this tutorial is for the Galaxy S2 (I9100) only.


  • Ensure download of appropriate USB drivers and enable USB debugging mode
  • Ensure device is rooted and ClockWorkMod (CWM) Recovery is installed
  • Ensure device is running Ice Cream Sandwich (ICS) bootloaders
  • Ensure device is not running a Kernel with the MMC-Superbrick-bug (If unsure, flash CWM Recovery using Odin/Heimdall)
  • Ensure all data is backed up
  • Ensure battery has at least 80 percent charge

To Install CM10.1 Android 4.2.1 ROM on Galaxy S2 (I9100)

  • Download CM10.1 Android 4.2.1 (Jelly Bean) ROM
  • Download Google apps package
  • Connect device to computer with USB cable and copy downloaded files, without extracting contents
  • Disconnect device and switch it off
  • Re-start device in Recovery mode (to do so, press Volume Up, Home and Power until screen flashes and then release buttons; an alternate method can be found here)
  • In Recovery, perform Nandroid back-up of present ROM (to do so, select Backup and Restore > Backup and return to Recovery menu after action is completed)
  • Wipe data on device (to do so, select Wipe Data/Factory Reset > Yes and return to Recovery menu after action is completed)
  • Use Volume keys to scroll to Install Zip from SD Card, select with Power and then highlight and select Choose Zip from SD Card
  • Locate ROM file, select using Power and confirm installation
  • After installation, repeat selection process to install Google apps package
  • After installation return to Recovery menu and select Reboot System now (first reboot may take some time)
    • Note: To return to previous ROM, boot into Recovery > Backup and Restore > Restore and select ROM from list

The CM10.1 Jelly Bean custom firmware, based on Android 4.2.1, is now installed and running on the Samsung Galaxy S2 (I9100) Navigate to Settings > About Phone to verify software version.

[Source: Android Jinn]