QUOTE(AlexZai123 @ Jul 22 2012, 10:07 PM)
Hey guys there! I'm new to smartphone! And Galaxy S2 is my first and new smartphone. Bought it last week. Since I don't know anything about smartphone, I heard that Galaxy S2 comes with Android 2.3.6. So I requested the dealer to help me upgrade to 4.0.3 ICS.
After that only I discover there are many bugs there, lagging in temple run, and sometimes do stunned at screen. My friend's S2 won't and he havent yet upgrade to ICS. Both of us are I9100G. And I9100G is downgraded version right? Compared to I9100 version.
Here are my questions:
1. I heard all of them talking about rooting Android. I know its point is to gain full access to phone right? And some say rooting can void the warranty. After rooting can I unroot it safely? without bricking the phone?
2. Can I downgrade from 4.0.3 to 2.3.6? Or need to re-flash to install back 2.3.6?
3. I also heard about binary counters in S2, once rooting is done or a custom OS is flashed will trigger the binary counters? And this will void warranty too? Is there a maximum count? Once we reached the maximum we won't be able to flash things anymore, does this exist?
4. Can you guys teach me how to reflash back to 2.3.6 safely? Thanks in advance!
Your answers and helps are much appreciated.

1. yes, officially root void waranty, but can unroot, and flash back stock rom. they wont be any trace. unlike HTC phones.
2. yes you can also. but really no point in doing so. the 2.3.6 one alot of issues. ICS really saves the G version.
3. can use USB jig, i read that there is a new root method that doesnt increase counter.
http://forum.xda-developers.com/showthread.php?t=17467944. all the info you need to know is in 1st page. read em.
*there really is not need to flash back 2.3.6. maybe do a factory reset,
or flash CM9 for your phone.
http://forum.xda-developers.com/showthread.php?t=1583091