I have a Gateway FX7026 i first did a clean install of Linux 19.2 0n which wouldn't shutdown/power off when i tried to just turn it off.
I re-installed it to get the same results.
I Tried the new LinuxMintCinnamon20.04 Ulyana with the same results.
In both linux distros i installed all the updates.
I tried to shutdown by using the the shutdown icons
The Linux20.04 works fine on another computer where i installed it.
I Reinstalled the original W7 Home with Chrome browser and everything works fine.

FX7026
Q9300 CPU quad CPU
8gb RAM
250GB SSD

Don't know why Linux will not work properly on this machine.
Is there such a thing as hardware incompatibility??

What happens if you use the terminal and enter `sudo poweroff -f`?

And what's your video card? Some quick reading says that Mint users have had this issue with nVidia drivers not being properly installed.

I tried sudo poweroff -f which did not work
The mobo has onboard video
I don't recall trying nvidia drivers
Next time i'll try nvidia drivers
Thx for the suggestions