I have one Intel-based computer which does want to poweroff with newer linuxes. To get this computer to shutdown completely, it can do via Terminal or script using command

su -c 'shutdown -h 0 && /sbin/poweroff -d -f -h -i '

If that script does not work, the next brutal script works:

#! /bin/bash

sync && xterm -e "sudo sync ; sudo systemctl --force --force poweroff"

Xterm is needed for that script.

User force log out can do the next command:

pkill -KILL -u username