Thanks.
Typing in Terminal
sudo nvram boot-args=""
and the password when prompted afterwads, and then carriage return reboots automatically.
But it gets stuck again in the command-line console.
Typing exit and pressing the carriage return there (all blind, since I see no feedback on the screen) goes to the VM Desktop after a few seconds, but if I reboot or shut down and boot, the issue persists (shows again the command-line console).