Steve, some magic has happened: I renamed the site folder to what I used to be before I tried to upgrade, changed the name of the folder in xml file, as you've recommended, and I got a whole new bunch of new options in the "Actions" drop-down, including the "Upgrade" one. I clicked on it and it shows life. I see this:
Your site will be running faster
Sitefinity is going to perform database optimization procedure which may take up to 2 hours.
Up to 2 hours
The result of these optimizations will
affect page performance during edit, publishing and frontend startup
time — e.g. your site will be running faster.
Please note that:
- It's advisable to have backup of your database, even there is no risk of losing any data.
- The site should not be used in production during the optimization procedure.