Frozen iPhone 14 will not "shut down"

I have an iPhone 14 and it has functioned just fine until two days ago.

As I have done hundreds of times before, I tried to "reboot" my iPhone Saturday by holding the appropriate buttons down until I got the usual screen with a "slider" at the top with an on/off button on the left side plus instructions to: "slide to power off" After powering off, I was going to start the phone up again, completing the "reboot"

HOWEVER, that familiar slider at the top was COMPLETELY unresponsive to ANY touch. After a few seconds the phone would turn off.

Although I turned it back on numerous times, there was still no slider response to any finger touch.

At that point, the ONLY response I could get was to hold the buttons on either side down for a few seconds until the phone started a ten second "countdown" before it would send out an "emergency SOS call" Turning the phone off halted that countdown (Thankfully!)

This morning (Monday) I tried again, trying various combinations of button-pressing with no results...EXCEPT now the phone will not turn off at all.

HELP! Any ideas, anyone?