I am getting a 500 error when I try to manage my blog. It happened right after I activated a child theme. I navigated to wp-contents/themes to try and delete the last theme I activated or change its name.. something I thought would force the default theme to activate. I am not able to open, edit, delete, or change the name of the theme. Is there any other way to force another theme to activate or anything else I can do to fix this error?