Catalina install reboots but doesn't finish

I want to upgrade my Mojave 10.14.4 machine to Catalina. While running under a normal boot, I started up the Catalina install file and it started up just fine, then counted down remaining minutes from about 26 to maybe 3 minutes, then wanted to reboot. So I rebooted. When it came back, it didn't apparently realize it was in the middle of an install so it did nothing else, and it still shows running Mojave 10.14.4.

Is there a way to kickstart the install back to finish up?

Author: pizzaguy