Mini won't shut down after attemting to install Monterey
I tried to install Monterey on my Mac Mini. This particular Mac mini was introduced in late 2014 which, based on the table on Apple Support is compatible. The OS downloads and spends a good hour setting itself up. If I remember correctly, it even tells me to restart my mini to start the install. Nothing happens. The Mini won't restart. I've used the off switch to turn the mini off and on. Thankfully the Mini does come up.
The OS is still Big Sur. However, when I try shut down the mini using Shut Down or Restart in finder or any other of the ways to shut it down, it clears the desktop and goes do farther. I've even logoff my account and tried to shut down using the available accounts screen. Nogo.
The mouse can move the cursor but nothing else happens. No menus, just an empty desktop with the usual but empty desktop background.
Any help would be appreciated.
Thanks
MG