Are you sure you extracted the new files into System/Flash UI/?
You might try to delete "mainmenu1.swf" (or however you called Cheetah Pre-Beta), then extract the archive into System/Flash UI/ and then rename "mainmenuN.swf" to "mainmenu1.swf" (or whatever number you want to insert).
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audio setup: Cowon J3 32gb | Cowon Z2 16gb | Audio Technica ATH-M50
other: Galaxy Nexus | Nexus 7