Guys,
i recently bought a Samsung Galaxy S2, G version and rooted with a custom kernel.
Now my screen is sometimes flickering, and i want to send it to warranty.
How can i unroot my phone and restore back to factory setting?

1. Is it enough by performing hard reset?
2. If i am using SuperOneClick to unroot, is there any file that i should download?
3. If i update my phone to latest update, is it will be the same as unroot?

which method should i use?
or should i follow these step:
http://www.teamandroid.com/2012/04/03/inst...laxy-s2-i9100g/
i am not sure if link above is sufficient enough or not