There appears to be a problem with the Cellular radio. As directed on the screen, contact your Cellular carrier - or Apple Support.
You can contact the Support Team using the Get Support link at top-right of this page. Alternatively, if you have access to another Apple device, you can initiate and manage your support cases using the Apple Support App. If not already installed on your device, the App can be downloaded from the App Store:
https://apps.apple.com/gb/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 test and assess your iPad:
Genius Bar Reservation and Apple Support Options - Apple
Given the evident damage to your iPad, other faults may exist.