Even that old machine would/should power down if you press and hold the power button for 4 seconds.
The issue has thousands of web pages about it so I won't duplicate prior ideas. Today if I don't spot the issue in a few minutes we reload the OS since troubleshooting costs skyrocket and the owner does not want to pay the usual 500+ bucks for a day of troubleshooting.
You bring up a good point. Did Microsoft blow it by not supply OS repair tools that actually work? It's like a car that an air filter failure means you replace the engine.
Still runs well but does not shut down. BLUE SCREEN WITH MESSAGE SHUTTING DOWN......Have to pull the power plug after two or three minutes to stop it. It does not start up in Safe Mode so assume it has actually shut down.