First Place a fastboot.exe file in your SDK/Tools (or Platform-Tools) folder (same as your adb.exe file) if it is not there already. [Download]
Instructions: (video coming soon)
1. Download the Android 4.0.2 factory images to your PC. [Download]
Android 4.1.1 JRO03O Download
2. Unzip the file and its contents into your SDK/Tools folder (wherever your adb.exe and fastboot.exe files are).
*Make sure they are not in their own folder, but have all been extracted to Tools.
3. From within your Tools folder, open a command prompt (SHIFT + right click – “open command prompt here”):
4. Type the following commands, allowing each to finish before moving onto the next:
adb reboot bootloader
fastboot flash bootloader bootloader-toro-primekk15.img
fastboot flash radio radio-toro-i515.ek02.img
fastboot flash radio-cdma radio-cdma-toro-i515.ek05.img
fastboot -w update image-mysid-icl53f.zip
fastboot oem lock
5. Reboot your phone by highlighting “Start” and pressing the lock switch.
6. It really is as simple as that. Your phone is now back to a 100% stock, unrooted and locked state.