That error number refers to a failure of the JavaScript on your wp-login.php page. In your case the initial ajax call is working but it returns a black script, so the code to validate your login is not loading at all.
You also have another form of login protection on your login page, I’m not sure if that is interfering but I don’t think so.
I think that there is something else intercepting the ajax calls and prematurely returning a blank response. I would like to help you get to the bottom of this and fix it so you can login again. Would you be willing to send me your FTP login so that I can find the source of the conflict?
Please reply to this email directly, do not post you login information on this forum 
