Database won't update after core update

Hi,

I’m working on updating a website from 7.2.1 to the latest Drupal 7 release (7.53). I did a manual core update. Then ran update of modules and themes. Next step is updating the database, but it doesn’t go through. The Drupal database update page is stuck on the “Overview” stage, and when I press “Continue” it just remains on the same page (the url changes, though). At the same time, I’m logged in as admin, and can view admin pages, but cannot complete any operation. I either get an “access denied” or a notification that the form is out of date (and changes made are not saved).

The site also lost its theme and non-English content does not show, but that’s something I’ll try to figure out myself first, once I get admin to work.

Any ideas what that could be? Possible solutions? (I’ll also be on live chat with my hosting to see if they can do anything on their end, but I think that’s beyond their ken).

Background: The site is being updated because of two recent hacks. User 1 was compromised (I couldn’t delete it, but changed all login details). Additional users were created and deleted. Of course, all that was done before the update; can’t edit anything or delete anyone now.

More background: I’m not a Drupal expert, and not a tech expert. I’m also not the person who built the site, but I’m the only one with enough technical understanding to do something that we have. So I might be a bit slow in understanding things that look trivial to you folks 🙂

Thanks in advance to everyone!

Drupal version: 


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