I understand your frustration with Illustrator Beta not launching. I'm here to assist you in resolving this matter. We released a new beta, v28.0.0.10 today. You can manually try updating to this version from the Creative Cloud desktop app and see if it resolves the issue.
If that doesn't help, would you mind confirming the OS version and other system details? Also, please confirm whether the public (GA) version of Illustrator is working.
If the issue still remains, don't hesitate to reach out for further assistance. We're here to help!