wp-admin: "Sorry, you are not allowed to access this page."

After 2 weeks not using our WP site, logging into /wp-admin/ gives a whitescreen error:

Sorry, you are not allowed to access this page.

I have:

• renamed plugins to plugins.temp.
• created a new admin user via phpMyAdmin. New user has user_meta role of a:1:{s:13:"administrator";s:1:"1";}.
• renamed themes to themes.temp.
• deleted core WordPress files, and replaced with newly uploaded files.
• replaced .htaccess with a default version.
• CHMOD all folders to 755 and all files to 644 recursively.
• turned on WP_DEBUG and found no errors.
• confirmed the site_url & home_url are set correctly in the options table of the db.

all without changing the error.

Help appreciated.