Board not upgraded after update

[Wires]

I'd suggest starting the upgrade process again. To verify your version of MyBB that your database is on, run the following query:

SELECT * FROM mybb_datacache WHERE title = 'version';

The result will look something like this:

a:2:{s:7:"version";s:6:"1.8.17";s:12:"version_code";i:1817;}

Can you see the version in bold? That will be the version your database is on. Now you need to get the right set of files to match your database version from here. You want to download the .zip and upload your files as usual. Once you configure your database and files to work with each other, see here to begin upgrading.