I turned on the laptop this morning and there was the Grime Fighter screen! I waited for the "Houston, we have a problem screen, but it never appeared." I Esc and chose the F12 option that took me to the Boot Manager screen with the Windows boot option highlighted. I hit enter and was able to login to Windows.
I noticed an Avast icon in the box at lower right. I touched it and a notice said, "Thank you for installing Avast!" It suggested that I activate, but I declined.
Attached are .jpg screenshots of Setup, Boot Manager, and the Avast! files directory now on my laptop.