Head to the folder WP-CONTENT and rename the plugins-test to plugins then your site may stop working again, so pinpoint the culprit inside that folder.
so far it looks like it s been fixed.
Check line 1924 of wp-db.php or line 1219 of pluggable.php
Maybe WordPress needs updated? Not sure there are so many things that can become an issue after previously using 3rd party plugins/themes