I have been waiting for OTA for several months with no luck. So finally decided to flush my Samsung Nexus S with Jelly Bean 4.1.2 factory image. Here is how I did it.
- (PC) Download Nexus Root Toolkit from here (don't worry. I did not root my phone, just unlocked it for flushing!).
- (PC) Install the software. When prompted, choose your device. In my case, it was Samsung Nexus S, 850MHz, i9020a. Allow the software to download necessary files for your phone.
- (PC) Connect your phone to the PC with a USB cable. Run the 'Nexus Root Toolkit' software and click on 'Unlock'. Follow the on screen instructions to unlock your phone.
- (PC) Download Nexus S factory image from here.
- (PC) Unzip the downloaded image in the installation directory of Nexus Root Toolkit. In my case the path was C:\Program Files\WugFresh Development\data
- (Phone) Turn off your device
- (Phone) Go to Bootloader (press&hold volume up button then press&hold power button)
- (PC) Go to the folder where you unzipped the factory image. Make sure that the folder contains adb.exe and fastboot.exe.
- (PC) Double click on flash-all.bat file. This will flush the factory image in the phone.
- (PC) When done, click on 'OEM Lock in the Nexus Root Toolkit to lock bootloader again.
Enjoy your Jelly Bean:)