Upgrade shows as successful but can't login

I upgraded from 2.7.1 to 2.13.1 via the web, and I got a “upgrade successful” response, but now I can’t log in. I’ve tried running John Linhart’s commands, but I still get an error on the login page.

On my first attempt to upgrade, I just clicked on the upgrade button within Mautic. The process started, but it ended with a blank webpage. Now, when I go to what used to be the log in page, I get:

The site is currently offline due to encountering an error. If the problem persists, please contact the system administrator.
System administrators, check server logs for errors.

“Uh oh! I think I broke it. If I do it again, please report me to the system administrator!”
500 Internal Server Error

In file manager, everything seems to still be there, and the version file shows as 2.13.1.

Thanks,
John

I’m not sure I follow you- what steps are you referring to?

I am the web server user. I’m on a shared hosting account at Hostmonster.