If your iPad is stuck in a boot-loop - and forced-restart fails and/or DFU restore is not accessible - you’ll need to seek assistance from Apple Support, or the technicians at the Genius Bar of your local Apple Store.
You can directly contact Apple Support using the Contact Support link at top-right of this page. Alternatively, if you have another working device, you can initiate a support case using the excellent Apple Support App. If the App is not already installed, it can be downloaded from the App Store:
https://apps.apple.com/gb/app/apple-support/id1130498044
Just to be sure that the forced-restart procedures are clearly known to you...
- 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 other iPad models: 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.
Note: If 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.