How do I fix a frozen iPhone screen that won't turn off?

Hello,

Try this:

1. Press and quickly release the volume up button.
2. Press and quickly release the volume down button.
3. Press and hold the side button until you see the Apple logo (could be as long as 30 seconds) 

The timing is a little critical, you may have to try it several times. See this for more detail:

If your iPhone, iPad, or iPod touch won‘t turn on or is frozen

Good luck.

I’ve had to do the hard reset several times in the past it will work :-)

and also when I’ve had the black screen death many times also.

its a good shortcut to remember and use for several issues.

(quickly press volume up button, then volume down button . Then press and hold side button on opposite side of phone until you see the apple logo appear again after it reboots itself)