Yea when I tried pressing the "ota update fix" button I kept getting this error message as shown in the screenshot. Then I would go press install now and it would reboot and come back to the setup screen asking for my credentials and the same update is still available to install. However, I don't know what I did but I pressed the "ota" update fix button when it finished downloading and all I had to do was press install and when I pressed the "ota update fix" button in the tool, I got a different message and it told me to prepare my patch usb and I got the Catalina installation splash screen as described.
One odd thing that happened during the install is that it froze during the install as it showed the apple logo with a spinning circular icon and not a progress bar and hung there for a while. I eventually just force shut off my Mac and then applied the patches from the dosdude1 usb. At first, I got a kernel panic but then when I picked force cache rebuild it worked fine. After redoing the patches everything seems to work now.
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