Did you try flashing CWM, CF Autoroot or TWRP recovery in Odin only to see a Kies error saying “Unauthorized software detected on phone” with an exclamation point? The fix for this is very simple. All you have to do is use a newer computer because chances are the computer you are using either has slow USB ports or is old computer.
After switching to a newer computer I noticed I booted up into CWM just fine.
You can also try switching USB cables because that makes a big difference.