Website hacked and backend is broken

A website I manage was infected with malware and there were alot of files that were marked suspicious.

The website opens on the front-end normally with minor issues regarding menus are blank. And I can login to the dashboard. But I can’t access any page in the backend. When I do I get a screen like this:

Some of the files were in the wp-includes directory. I cleaned up the database from tables without the configured table prefix and reinstalled WordPress. Also I’ve deleted some of the plugins that had infected files and manually updated others.