I had the same issue on Windows 10 and 2022 TurboTax Business - rebooted, tried all the troubleshooting steps, still got the "Waiting for the installer service" message no matter what I did.
With TT stuck at that message, I went into Task Manager using Crtl-Alt-Delete, set the view so I could see "Background processes" and found "Windows Installer" running. I clicked on this, then did End task.
As this is a key Windows component, it automatically restarted, and I was then able to do the TT update.
