Nexus S I9020 Gets Android 4.1.2 Update with JZO54K Slim Bean ROM [How to Install]
Photo: XDA Developers

Google Nexus devices and other Galaxy series smartphones have recently received a flurry of custom ROM Jelly Bean updates based on the latest Android 4.1.2 JZO54K AOSP ROM. Slim Bean is among the most popular versions of the JZO54K custom ROM release, due to its lightweight profile and a plethora of exciting features ported to it.

The JZO54K Slim Bean ROM is not an official release; but, rather a custom ROM based on stock AOSP firmware for Android 4.1.2 Jelly Bean. Hence, your Nexus S device should be rooted and ClockworkMod recovery installed on it before installing the JZO54K based firmware update.

Key Points to Note

    • The JZO54K Slim Bean ROM and the instructions given in this guide are applicable only to the Google Nexus S I9020 model and will not work on any other device. Verify your device's model number by navigating to Settings > About Phone.
    • Make sure you back up your favourite apps, important personal data and settings to avoid unexpected data loss while performing the Android 4.1.1 Jelly Bean update.
    • Enable USB debugging mode by navigating to Settings > Application > Development. This feature helps in connecting your Android phone with the computer.
    • Verify that your phone battery is at least 85 percent charged to prevent unexpected device shutdown (due to battery drain) while flashing the AOSP based JZO54K Slim Bean custom ROM or installing the Jelly Bean updates.
    • Ensure that your phone is factory unlocked and rooted. Also, verify that ClockworkMod (CWM) recovery is preinstalled before proceeding with the Android 4.1.2 firmware update.
    • The instructions provided in this guide are meant for reference purpose only and do not cover any warranty claims involving device damage or issues arising out of installing the Android 4.1.2 Slim Bean firmware update. Users are cautioned to proceed at their own risk.

How to Update Google Nexus S I9020 to Android 4.1.2 Jelly Bean with JZO54K Slim Bean ROM

Step 1 - Download Android 4.1.2 JZO54K Slim Bean and Google Apps for the Nexus S on your computer.

Step 2 - Connect and mount your Nexus S USB mass storage on your computer using an USB cable.

Step 3 - Copy the Android 4.1.2 ROM zip and Google Apps zip files to the root folder on your phone's SD card.

Step 4 - Power off your phone and boot into bootloader mode with a button sequence. To do so, press and hold Volume Up, Volume Down and Power buttons together until the device powers on and enters bootloader mode.

Step 5 - Follow the onscreen navigational instructions. Then choose the Bootloader option and progress into CWM Recovery mode.

Step 7 - In CWM recovery, perform a full data wipe first. Then navigate to flash zip from SD card option and hit the Power button to select it.

Step 8 - Tap the Power button again and click choose zip from SD card.

Step 9 - Use the volume keys to navigate to Android 4.1.2 ROM zip file and select it using the Power button. Confirm the ROM installation on next screen and the installation procedure should begin.

NOTE: Repeat this step for installing Google Apps as well.

Step 10 - Once the ROM is installed, hit Go Back and click reboot system now in the recovery menu. The phone will reboot and the first boot may take about 5 minutes to complete. So, leave it alone.

JZO54K Slim Bean ROM based Android 4.1.2 Jelly Bean update is now successfully installed on your Google Nexus S. Go to Settings > About phone to verify the firmware version installed.

[Source: Team Android]