No just upload the files from the 2.3.1 archive, the ones in the 'root' dir, to the root of your forum and it's updated.
It's not the years honey, it's the mileage...
I do not provide any install services for phpBB, Mods or Styles.
Please do not pm me for support/scripting help - you won't get any reply. If you have a question then make a post in the appropriate forum.