I appreciate you for performing the steps outlined in the article you shared, @GreenUpIT.
Since you're still unable to open your QuickBooks Desktop (QBDT), I highly suggest contacting our support team. One of your live agents can securely look into your account and fix what's preventing you from opening the program.
To reach out to them, feel free to utilize this link: https://quickbooks.intuit.com/learn-support/help/en-us/contact-us?product=QuickBooks%20Desktop
Once you're able to open your QBDT, you'll want to update the program to the latest release. This is to ensure your QuickBooks is packed with the newest features and fixes and to prevent any issues in the future.
You can count on me with any QuickBooks concerns you may have. I'll be here ready to answer them for you. Keep safe and stay healthy!