After an upgrade, a finishing script has to run with the first site load to make some final database touches. It's not enough to just run the sql part to successfully upgrade the database, you have to make sure that UpgradeProcedure.cs runs as well. It's the part that logs and UPGRADE - FINISH event to your Event log, without it the upgrade is incomplete. Two options to try - 1) run the code manually or 2) one of the database settings flags (CMSDBVersion, CMSDataVersion) triggers this procedure to run. You can for example install fresh 8.2 and upgrade it to 9, not run it, and connect it do your db and the script would finalize your db upgrade. Or try to observe how the mentioned flags work during the upgrade and do some magic with your own db. Make sure to do backups at any step.
Of course the safest way to do it would be to roll back and do both again as Trevor mentions.