my iphone x wont turn off

Try a forced restart.

• Press and quickly release the volume up button

• Press and quickly release the volume down button

• Press and hold the side button.

• When the Apple logo appears, release the button.

Force restart iPhone - Apple Support (IN)

Try this steps Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the side button. When the Apple logo appears, release the button.

Are you holding the volume up or down button and side power button in at the same time until you see the slider to shut down?

You're welcome, glad you got it fixed!