We are showing you here the tutorial guide to debrand your Samsung Galaxy S II, change the CSC code and then again rebrand it to original firmware.
1. Download Odin v1.83
2. Download Samsung Kies based on your country location. For example, for UK you can download the kies here .
3. Install the kies. This will install the proper drivers that are needed for flashing.
4. Download the latest Samsung Simfree firmware based on your region. For example, for UK version get it here
5. Reboot your device in download mode.
6. Turn your phone on by holding Volume Down, Home and Power buttons.
7. Run Odin exe file.
8. Extract the zipped file that you downloaded in Step4. You will see a tar file in it.
9. Place the tar file in PDA in Odin.
10. Make sure you do the same settings as shown in below image.
11. You will see a yellow box on the left side of Odin. This means that you are ready to flash now. If you don’t see any yellow color box, it means that Samsung Kies is not installed properly. Go to Step2.
12. Press Start on Odin.
13. You will see a progress meter on Odin. It will flash all the necessary files.
14. After flashing is done, the smartphone will reboot on its own.
15. After reboot, you will see a debranded SGS2.
16. You need to change now your CSC code.
17. Type this code in the phone dialer *#272*<your IMEI number>#
18. Press Home, Volume Up and Power keys at same time and you will enter into Recovery.
19. Do a Factory reset.
20. Reboot the smartphone.
21. Check the CSC code. It should say ‘XEU’.
22. Rebrand the firmware back to O2 Original Firmware for the warranty purposes. Download Original ROM from here
23. Follow the instructions from Step5 upto Step15.