ipad screen frozen slide to power off frozen

Help!

I have tried the solutions at Apple site - no joy (eg: pressed vol up, vol down and power buttons etc as directed). The “slide to power off” option is visible on screen but screen is frozen so I can’t power off and re-boot. Ipad does not have home button - newer model.

Battery is fully charged.

I have left it plugged in for an hour - still no joy.

What do I do to get into device to try and restart it and unfreeze it?

Thanks people

MM