Originally Posted by clsA
you only need the one step
Edit Sorry yes if your on stock recovery you have to install custom recovery and root
then lock then remove root and flash back stock recovery ..done
Thanks for the help. Here is what worked: I unlocked, flashed CWM, flashed SU, did the "echo -ne '\x00\x00\x00\x00' | dd of=/dev/block/mmcblk0p3 bs=1 seek=33796" line from fastboot, flashed the RUU.zip, then finally did "fastboot oem writesecureflag 3" which put S-ON.
I'm now back to a factory AT&T image, S-ON, and locked bootloader. All ready to be returned.