I have followed the following 2 tutorials on how to unroot and get S=ON on the MyTouch 4g:
http://forum.xda-developers.com/showthread.php?t=834225
I have successfully reverted to the stock ROM and unrooted the phone, but I still have S=OFF. When I run the first one in the emulator, it gets all the way through execution and tells me to reboot into hboot to get s=ON, but when I do that, it still shows S=OFF:
Duplicating hboot
2048+0 records in
2048+0 records out
1048576 bytes transferred in 0.563 secs (1862479 bytes/sec)
Synchronizing
Powerdown and reboot into hboot to check s=on
I really would like to get S=ON so that I can ask my provider for service if I need it.