My page is downloaded when you enter the domain and I do not know what this error is.
When I add this to the htacces the page is not downloaded but error 500
AddHandler application/x-httpd-php56 .php .php5 .php4 .php3
to test the page link
It's really strange, something like this has never happened to me.
You could try renaming the .htaccess file and checking again what happens or entering the IP link where nameX is your name user to enter the control panel or the first letters of it (they are only the first 5 characters).