The Error I get is "Sorry, something went wrong. The tag contains duplicate 'input' attributes. Web Parts Maintenance Page: If you have permission, you can use this page to temporarily close Web Parts or remove personal settings. For more information, contact your site administrator."
I have attempted to add '?contents=1' to the Site Page URL "http://servername/SitePages/MockupData.aspx?contents=1" and I get the following error: "The requested page was not found or could not be loaded."
Finally, the page cannot be opened in SPD, it says 'Server cannot open page. The tag contains duplicate 'input' attributes.' I have no idea how to open the page to fix it. I have access to Central Admin. Thank you!