steps: Step 1 : Turn on the Galaxy S2
Step 2: Connect your phone to PC via USB
Step 3: Open Odin
Step 4 : Download the CF -Root kernel corresponding to your
Step 5: On your PC, unzip the zImage file with 7- Zip ( or any other decompressor)
Step 6: Copy the zImage file to the phone's SD card
Step 7 : Download the stock kernel (kernel factory ) for
Step 8: . Unzip the file to get the tar file containing the kernel
Step 9: Remove the USB cable from the phone
Step 10: Turn off the phone
Step 11: Enter download mode (by pressing the buttons " Volume Down " + " Home " + "Power" at the same time ) Step 12: Press " Add volume " when the warning comes up. Odin download mode will
Step 13: Reconnect the USB cable to the phone
Step 14: In Odin, click PDA
Step 15: Select the kernel tarball .
Step 16 : Click on Start
Step 17: When we see a "PASS ! " green on Odin, remove the USB cable
Step 18: When you start Android, open CWM Manager
Step 19: Select Flash kernel
Step 20 : Browse and select the zImage file, and click on Flash Now when you start the phone should not appear the yellow triangle ! : cheers :