Something like 'she didn't manage to fake her singing'? That's not what I would call "got messed up"
Why would she clearly be singing what looks like an alternate melody line that doesn't match up with the video quite a bit of time if she wasn't singing mostly live? Mariah has NEVER done anything like that ever.
She wasnt even trying to lipsynch the song, i mean you can tell she's not hearing the tracks clearly, it was a sound issue but this is ATRL so... uhmmm whatever