Site update sticks with “Briefly unavailable for scheduled maintenance. Check back in a minute.” or “The website is undergoing scheduled maintenance” message.
Connect using FTP and delete the .maintenance file in the root directory.
Other checks
Are you sure the message being shown isn’t your own dummy message for a site you’ve haven’t finished creating yet?!!
The wordpress updates Page
This is the URL for the updates page
http://mysite.com/wp-admin/update-core.php
Feel free to comment if you can add help to this page or point out issues and solutions you have found. I do not provide support on this site, if you need help with a problem head over to stack overflow.