How to Show/Hide Image with Multi-state

I’ve created a multi-state box using the ‘Empty State’ template and deleting all of its formatting/text/images. (I didn’t use the ‘Blank’ template, because I wouldn’t be able to get rid of the border around it.) I’d like to add an image that will show/hide when the user clicks the “Read more” link to expand/collapse the additional text. Is this possible? (I cannot view/edit the ids for the buttons/boxes in the ‘Empty State’ template, so I’m not sure how to make this happen.)