Have you tried the poweroff command yet?
I use OpenRC, with XFCE4 and startx auto login, and have no trouble shutting down via the graphical menu, or by using
$ sudo poweroff
But when I tried using either
$ sudo su
# shutdown now
$ sudo shutdown now
it did not shutdown. Rather it started shutting down, then said:
Cannot open access to console, the root account is locked.
See sulogin(8) man page for more details.
Press Enter to continue.
Pressing enter restarted the system.
When I used to use shutdown on Debian I used shutdown -Ph now I think anyway, it needed some args to work, but they vary on different distros. However, trying that still did not work, it started shutting down then froze and required a hard power off from the power button, ending with the message:
Sending the final term signal
Sending the final kill signal
[1248.507739] reboot: System halted
[1248.567527] MMI: PCI system error (SERR) for reason b0 on CPU 0.
[1248.567527] Dazed and confused, but trying to continue
_
My current usual terminal command is:
$ sudo poweroff && exit
because that closes the terminal window you are in so everything can be shut before shutdown. And it works which is helpful.