Unroot/Unbrick the Nexus S (4G)
This video will show you the latest and easiest method to unroot or unbrick your Google Samsung Nexus S or Nexus S 4G. This will take you back to the latest stock software on your device. Any questions, just ask.
Wugfresh Toolkit:
http://www.wugfresh.com/nrt/
How to root (if needed to help setup your PC):
http://youtu.be/V75F1M79eCY