We installed a plugin to show our site offline for a few days during an update. But after finishing the update we cant remove the "Site offline" message. Finally we uninstalled the plugin, but the frontpage still shows "Site offline". Any suggestions om how to get the site "online" again? ( no, plugin developer does not answer our emails..)
Check for a .maintenance file (if so, delete it) in your wp root and also check your .htaccess file
I could be that the plugin added some wired thing as DB-option that gets autoloaded. Please check your DB-Options table for unknown keys/values. Then do cross file searches inside the plugins folder for the key.