Can you get to your site admin? I am guessing a couple of things might have gone wrong during the update.
1) All the files didn't get copied correctly
2) The update had issues or was done incorrectly such as just overwriting existing files.
3) It could be a permissions issue with the files. Try resetting those.
What might fix this is to download the latest version of Fordson. Unzip it on your local computer. Then FTP the fordson theme directory to your theme folder on the server. Sounds like you might be missing a file or two from doing the update. Clear Moodle cache and it should work.
Unless you did a snapshot then downgrading might cause more issues.