the screen has frozen when I slide down the control centre

If iPad isn’t responding, do one of the following:

• On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
• On an iPad with Face ID: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.

If your iPad still doesn’t turn on, or if it gets stuck during start up, see the Apple Support article If your iPhone, iPad, or iPod touch won’t turn on or is frozen.

Have you tried a simple hard reset of your iPad by holding down both the Home and the top single sleep/wake/power buttons simultaneously until your iPad goes to black and restarts with Apple logo, then release the buttons?

Good Luck!

Force restart your iPad, hold the home and power button at the same time.

Good luck.

(Let me know if it worked.)