Forgot to add: the OP's procedure applies to anyone who used unrEVOked to root their phone. For those people who rooted before unrEVOked was a full root, you can skip steps 1-7 (switching S-OFF to S-ON) and just run the RUU described in step 8.
If you can't remember, check your HBOOT screen. If you see ENG S-OFF in the top line, you didn't use unrEVOked. You have the Engineering HBOOT, and if you try to flip that to S-ON with unrEVOked's S-ON tool, it won't work. Just apply the RUU. It will overwrite the ENG HBOOT with a SHIP HBOOT that will be S-ON.
The good thing about science is that it's true whether or not you believe in it. -Neil deGrasse Tyson
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