the button never mattered
even if they had found the button during the original investigation, it wouldn't have made any difference. at best it would suggest that one aspect of her story might have been true
but even if the button somehow could miraculously clear her, it still wouldn't warrant the end scene with the detective almost finding it. even if they did prove her innocent, it'd be too late. she'd still be guilty of the jailbreak and could potentially face charges as an accomplice to the other crimes he committed to break her out. pretty sure there's no statute of limitations on escaping from prison so they'd still have to stay in hiding
~~~
"I don't care, I'm still free. You can't take the sky from me..."