burger menu accessibility

My client’s accessibility consultants said this about the burger menu on https://abodecommunities.org/ (at widths narrower than 990px):

“The hamburger menu element is incorrectly defined as a link when it should be defined as a button. Also, the hamburger menu element does not alert the user if the menu is expanded or not.” — Does that sound correct to you, and if so can you help me address those issues?

Thanks and lmk if you have any questions!