Jetpack Carousel Close Button

Thanks in advance. We are using the Jetpack Carousel, but I really want to modify the close button, people tell me they can’t figure out how to get out of the Carousel. In FireBug the code reads:

<div class=”jp-carousel-close-hint” style=”position: fixed;”>
<span>×</span>

I would like to change the “X” to “Close Slideshow”. Firebug lets me do this, but I can’t find where the files are to make the change permanent. I searched the code in every file in the Carousel part of the Jetpack plugin, but couldn’t find it anywhere.

A little help? Thanks!