So the official Android 4.0 Ice Cream Sandwich OS update for the Samsung-made Google Nexus S handsets is now live and ready to be downloaded. The update has begun rolling out as an OTA update. Make sure to keep checking for the update, you should be able to get yours too. Sick of waiting for your Nexus S to get the OTA update to Android 4.0 ice Cream Sandwich? You should be thankful to Google – you can now install the update manually, as Google made the file available for download. This is specifically for T-Mobile branded Nexus S version. Don’t try it on CDMA version of the Nexus S.
How To Upgrade Nexus S To Android 4.0 ICS Manually
Simply download the file from the below links and follow the step-by-step instructions provided here at below.
1. Download the Google Nexus S Android 4.0 OTA Update package (hit the link).
2. Rename the file to update.zip (You can also rename the file to update to avoid it being renamed to update.zip.zip)
3. Connect your Nexus S to your PC machine and transfer the file to the root of the microSD card (inside no folders)
4. Power down the Nexus S. Now reboot the handset into the bootloader by holding the Power and Volume Down at the same time.
5. You should now see a screen with Androids on skateboards. Using the Volume keys, select Recovery button and press Power button.
6. The recovery screen will only show a triangle with an exclamation point in it. To get to the recovery menu keep pressing Power and Volume Up at the same time.
7. Now scroll down and select “Apply update from /sdcard.” to start the update.
8. Once the update has completed, reboot your Nexus S handset.
9. That’s it. Enjoy Android 4.0 ICS goodies on your Nexus S handset.
Source: Google