Rooting and modding Samsung Galaxy S2

If you just have to mess with your phone all the time and try out every option and setting, you'll probably have heard about replacing stock software with custom kernels and flashing in mods. This could expand battery life, give you new features and make your phone faster.

It can also render your latest phone investment as useful as a brick. Yeah, brick. That's what they call it when either you or some software you tried to run makes your phone shut down for good and it will never boot up again. So be warned, even though I am about to tell you how to possibly avoid it.

I DO NO TAKE RESPONSIBILITY FOR YOUR ACTIONS! YOUR PHONE IS YOUR OWN AND ANY OF THIS WILL VOID YOUR WARRANTY!

And don't try to be clever, the phone will tell your technician that you installed a custom binary. This feature is called the 'ROM counter'.

• First of all, some phones are known to have a bad FLASH chip, and this includes most versions of the Samsung Galaxy S2, from what I can read. 
• Personally I have the GT-I9100 which came with GingerBread 2.3.5. 
• If you, like me, have Samsung Kies installed (if not, do that NOW) and updated the firmware, you will discover that GingerBread 2.3.5 will be updated to Ice Cream Sandwich 4.0.4.

At this point, download the following:

• Siyah kernel - Will give you a temporary rooted phone. Get the correct version, and put it on your SD card.  (you do need an SD card)
• ClockWorkRecoveryMod (aka CWM)

There is a particular problem that seems to come with the stock ICS 4.0.4 when you install the 'clockworkrecovery' mod. Therefore, first of all you need to root your phone to be able to actually check your phone. (with Siyah)

• Heimdall Suite 1.3.2
• CyanogenMod verison 9 (aka CM)

You also want the Google Apps extras

1. At this point, you have to boot up into recovery mode, and wipe the phone and the cache. 
2. Then, load this binary into the phone. 
3. When it reboots, it will show you a yellow triangle below the Galaxy logo at bootup, and if you go to Settings->About Phone you will see that the kernel has been replaced. 
4. If you forget to wipe the cache as well, the phone will not boot. (It is not bricked, just repeat the process.)

Then download an app called eMMC checker from the Play Store. Move CM and Google Apps over to the SDcard.

1. Download eMMC Brickbug Check from Play Store
2. Run check. It will probably say 'Insane chip: Yes' and then you must check the memory, for which you need to have the phone already rooted.
3. If the memory check passes, your phone's flash chip is functioning well enough to flash the ROM, but it will still kill it of you skip to the CWM step now!

Note: Just to be clear, both the memory needs to be OK and the Siyah kernel must be installed or else you will have a dead phone before this tutorial is over.

1. Boot phone into Recovery Mode. (Home + Vol Up + Power.
2. Hold until logo appears, release keys.
3. You will be presented with the recovery menu. Some phones has alternate combinations.

Lastly:

1. Wipe and factory reset
2. Wipe cache
3. Install CM from SDcard
4. Install Apps from SDcard
5. Reboot phone

Now, when you reboot, the phone will be a completely different beast. Modded or not, the S2 and S3 are  formidable devices, featuring multi-core CPU and GPU processing, as well as standardized USB connectors, an array of special-purpose sensor chips and last, but not least, a Linux-based operating system to glue it all together. With the right add-ons installed, your phone is essentially a powerful hand-held computer that can be used for a multitude of uses. While the comparison  is not fair, I would guess an S2 outperforms 5 year old laptops.

I think this was everything. Please comment if I missed something.

Anyway, here's the result: