Hold the power button down for about 5 seconds, this should force a shutdown. Once it's off, remove the power adapter and hold the power button down for about 30 seconds to do a power reset. Hopefully this will solve your issues but if it doesn't then you'll need to contact Support again and speak to a real support rep. 

Nope did not work . Now the power button is yellow. And again it just keeps turning back on.......

I held it for about 30 seconds as it tried to turn on and it finally shut off. But I can not imagine that is good for the long term

There's a good chance that it's a Windows issue and not the laptop. Does it still refuse to turn off now that you finally got it to? 

If it continues, try running a scan. Open command prompt as admin and enter the command sfc /scannow

Hi

In the old days, I would mention this option ...........

of unticking the Auto-Restart option, but W11 is so much more sophisticated it seems unnecessary.

Finally got tech support- they spend abot 30 minute reloaded the dell support assist and something else- now it all works (hope it stays that way...)

@mattyb3​ and take note of any thing in BIOS is about to get factory setting