I just ran the upgrade process. It claimed success
I changed the admin folder name.
The cart seems to work.
When I attempt to access the admin page I get a page that starts with
"You are seeing this page for one or more reasons:"
Then it lists config.php and database reasons.

I have made the config.php read only
I deleted the install directory
The admin/config.php admin paths apparently don't matter in 1.54

Is there a log file or something to help narrow in on the source of this issue?