I've done all the above and it doesn't work. I noticed on the manual upgrade this step (written for version 3.2):
Step 1.5: Remove .maintenance file
If you're upgrading manually after a failed auto-upgrade, delete the file .maintenance from your WordPress directory using FTP. This will remove the "failed update" nag message.
I have no such file.
I've used CPanel and then Filezilla - can't find that file at all, I keep getting the message,
No Update Required
Your WordPress database is already up-to-date!
But I cannot access my wp-admin. I've tried phpMyAdmin to set all plugins to the mentioned setting "0" and that didn't work...all this caused by a plugin called Backup Creator which wasn't ready for WP 3.3 (?!)...it was a premium plugin and has wreaked havoc on 4 of my sites.
I have out of 6 affected sites, resurrected my most important 2, including http://theaveragegenius.net - but what I don't understand is that in those 2 resurrected/working sites, both running Backup Creator, all I did was use CPanel to delete my Backup Creator plugin.
It didn't work subsequently...now I'm down 4 sites and hours of lost time - the manual install didn't work.
Help would be appreciated.