Good day! I installed Ubuntu Mate 16, 18, 20 LTS on a computer with a GA-J1800N-D2H motherboard. With any version of Ubuntu MATE, a reboot occurs upon shutdown! Bios updated but did not help.
Help! Help! How to fix it?
Hi 
Many people got same issue, it was mostly solved, sometimes some HW issues.
Please use the forum search function with words "shutdown acpi", you will find your answers
Thank! But the solutions described on the forum do not help to solve the problem ...
Did you try to upgrade your kernel ?
This might be a problem that power manager utilities could solve.
First install pm-utils:
sudo apt install pm-utils
Then issue the following command:
sudo pm-suspend
Your screen should display nothing. Check to see if pressing any key will awaken your computer. On my old laptop I had to press the power button to get out of suspend. If you get out of suspend, then issue the following command:
sudo poweroff
This should shut down your computer. On one of my machines where I use this command almost exclusively to shut down, I had to look at and change my BIOS configuration to allow a shut down without getting a reboot within 6 to 8 seconds after shutting down.
Good luck Lebedew.
Similar problem i have on manjaro-mate but i had install drivers on system.
The pc turned off but the fan still running ... I had turn it from power button to stop.
I' ve seen lots of comments on issues of restarting Ubuntu (and even Debian). I have a Gigabyte PC and the main issue was that the BIOS was to old for these more modern OSs.
So I updated the BIOS (Needed FreeDOS and other tools) and then it works like a charm.
So my advice here is to first check if there is a new BIOS available for your system(s) and update that first. And then go further if investigation is still needed.