Unless your "good" and by meaning good....I don't know "how good", you must be able to remove ALL traces of running CFW or homebrew. That means removing all log entries - error reporting and whatever else is hidden. If Nintendo looks over I'm sure they can easily detect software tampering - so I wouldn't trust a warranty repair to have a good outcome - they probably do a hardware mod anyway to stop cfw ability regardless. Don't know about that last one