I'm not the best with the Codebreaker Exploit but try this:
Ensure that your USB Device is
1) properly connected
2) compatible with your version of Codebreaker
Also, are you trying to boot FreeMcBoot directly? This won't work, you MUST boot uLaunch.elf first.
Here is the Codebreaker guide I would recommend.
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I have another exploit if your Codebreaker is not working.