Hi everyone, So what I did here was install Android 4.1.2 with Odin a while ago because in Mexico the S2 can't have any version after 4.0.4. And also I installed an insecure kernel so I could have root access. Now I want to go back to the original android OS the S2 included when I bought it and the original kernel. I'm asking for simple manuals to leave the phone as when I bought it and the best way to backup my contact list, because I can't make the PC detect the phone anymore and I can't sync it with Kies anymore. Also the phone freezes constantly and the battery doesn't last as long as when I had Jellybean 4.0.4 (yes the battery is calibrated). Please help.