Sudden unresponsiveness of power and volume buttons on new iPad

If your iPad is unresponsive, connect your iPad to its Power Adapter. Then, while still connected to external power, try a forced-restart:

Force restart iPad (models with Face ID or with Touch ID in the top button)

If your iPad doesn’t have the Home button, do the following:

1. Press and quickly release the volume button nearest to the top button.
2. Press and quickly release the volume button farthest from the top button.
3. Press and hold the top button.
4. When the Apple logo appears, release the top button.

If you continue to experience difficulties, you would be best advised to seek assistance directly from Apple Support. You can contact the Support Team using the Support link at top-right or bottom-left of this page. Alternatively, you can initiate and manage your support cases from Apple devices using the excellent Apple Support App. If not already installed, the App can be downloaded from the App Store:

https://apps.apple.com/app/apple-support/id1130498044

You might also visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) - where the technicians will be able to assist with troubleshooting:

Genius Bar Reservation and Apple Support Options - Apple

So... the next step is to seek assistance from Apple Support - or visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP).

Have you actually tried?

While the iPad may not seem to respond, the described button sequence triggers a hardware restart.

Force restart iPad - Apple Support