Or you can flash only the stock kernel with odin method. You can get stock kernel here http://forum.xda-developers.com/showthread.php?t=1588737
Yellow triangle will be gone with this..
Sent from my GT-I9100G using XDA
The odin method is used to revert back to stock firmware. You can download latest firmware from samfirmware.com, unzip it with the reqiured passwords and flash it with odin as you did earlier. Everything will be back to normal...
Sent from my GT-...