TT macOS desktop 2020 stuck in update/install loop. It doesn't relaunch.

I have been using TT Home Biz 2020 macOS desktop edition for a while and it was working fine. But today when I started up TT tells me I must install updates, and after I clicked on the "Install Updates" button, it started the process of downloading and extracting, then it showed a button "Install and Relaunch. It did something but TT didn't start up by itself.
When I double-clicked the TT 2020 icon, it showed "Install Update" again.
I did this a few times, but it seems I'm in the infinite update loop. Help!