How to Update Galaxy S2 I9100G to Android 4.0.4 CM9 RC2 ICS Firmware

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Posted in: Tips & Tutorials

CyanogenMod 9 (CM9) development is almost complete with the final release just around the corner in the coming weeks. CM9 RC2 is now available for the Galaxy S2 I9100G variant. If you have not yet received the official Android 4.0.4 firmware update for your phone, then you should give this custom ROM a try.

This is not an official Android 4.1.1 Jelly Bean update, just a custom ROM. In this tutorial, we will guide you how to install Android 4.0.4 ICS (CM9) on your Galaxy S2 I9100G with complete steps. This tutorial requires you to have a rooted Galaxy S2 with a custom recovery (ClockworkMod) installed on your Android phone.

Galaxy S2

Disclaimer: All the tools, mods or ROMs mentioned below belong to their respective owners/developers. We ( or the developers are not to be held responsible if you damage or brick your device. We don’t have you on gun point to try out this tutorial 😉

Also read: How to Install CM10 Android 4.1.1 Jelly Bean on Galaxy S2 I9100G.

Make sure you have installed all your USB drivers for the Samsung Galaxy S II to connect it with the computer. Download Samsung Galaxy S II USB drivers! Apart from just the USB drivers, there are a few more things that you need to take care of.

1. You need to enable USB debugging mode. This helps to connect your Android phone with the PC. See here: How to Enable USB Debugging.

2. Your phone battery should be 80-85% charged. If your phone goes off suddenly because of battery, during flashing ROMs or installing mods and updates — your phone might go dead permanently. See here: How to Check Battery Percentage.

3. Backup all your important data that you might need as soon as your flash a new ROM, or make a backup for just in case, you never know when anything might go wrong. See below on how to backup data:

4. Your Samsung Galaxy S II should be factory unlocked. Additional instructions for locked Android devices will be added in the tutorial for unlocking devices.

Now, let’s proceed with the tutorial on the next page and install CM9 RC2 Android 4.0.4 ICS on your Galaxy S2 I9100G.

  • Daher

    I have tried this guide and a lot of others. None helped me install a custom rom on my GT-I9100G.

    Apparently there is no ROM on the phone, so everytime I boot it, I’m stuck in CWM Recovery, and when I install a ROM from this Recovery, I get the “SGS II” splash screen with the dreaded yellow triangle at the bottom.

  • aqib

    I have update this according to your instruction
    But my phone (galaxy s2 i9100g) stuck at boot and not turn on
    Please kindly reply me with best solution i am thankful to u

    • Go to ClockworkMod recovery and do a full data wipe again. Then try to turn on your phone. It should work fine now.

  • does this reduces ram?

    • No, this actually improves RAM to some extent.