I already tried that and get the same error:
Access denied to resource 'CMS'
Permission for UI element 'Administration' is required.
The hotfix shouldnt affect this simple login, at least according to the list of bugs fixed in the hotfix.
I agree the issue is related to permissions and roles but as far as I can see, the administrator user in in the correct admin roles and those admin roles have rows in the RoleUIElement table for the administration ui element as well.
What else could be missing?