Correct, that means that in your original, problem installation a file was corrupted during upload or you have an error in your config/db.php.
To update try this: Copy your Pepper from the old installation into the fresh installation. Then check to makes sure you still see the database connection error. If not, and the page is blank, one of the Pepper you uploaded during the update is at fault. Otherwise, copy your config/db.php from the old installation into the fresh one. Don’t visit the fresh copy in a browser yet. Rename the old Mint directory to something like mint-broken and rename the fresh directory to the original directories name, mint, then visit in a browser.
Blank page or your Mint working normally? If it’s still a blank page there’s a problem in your config/db.php. Compare your db.php with a fresh one using this FAQ as reference. Any glaring errors (unclosed quotes, unintentionally replaced array keys, missing commas or semi-colons)?