Android 4.1 Jelly Bean Arrives For Nexus S [Download]

Download the file, rename it using a file explorer (I recommend super manager 3.0 if you don’t already have one) to “update.zip” and move it to the main sd card partition, which means getting it out of any folders it’s in. Then turn off the phone and hold volume up+power to get into the bootloader. From there, use the volume and power buttons to get into the stock recovery, and in there hold volume up+power again (there’s a certain order you have to hold them in, but I forgot it, so just try both combinations; nothing bad will happen). When the menu appears, select “apply update from .zip” (not an exact quote, but you get the idea) and wait. Enjoy! Oh, and I should warn you: since I assume you haven’t rooted your phone, chances are you haven’t got a nandroid backup, which means you’ve got no way to fix your phone in the unlikely event something goes wrong (I’m not responsible for your phone or any potential problems caused by my instructions, just saying), so you should look into that.