Kevin,
Next to last ditch attempt, switch to the classic template and see if the blog page loads....might have to manually enter it, but even this does not work with your current template.
If the above does not work some core file must be altered versus overriden in your last site re-make
Now Last ditch effort - create another install - maybe in a subdomain
Fresh files - add import the live DB. Add a blog. add the link in ZenCart
Or if you are handy avoid all the last stuf and copy/FTP the files to your local and diff/merge them against a default set and you should see no differing files that you can not explain - You might stick to just the /includes dir for this