Unless you are able to successfully restart the iPad, you will not be able to erase the iPad.
To erase the iPad from iPad settings, you must be able to successfully enter your Passcode. Similarly, to erase the iPad using Find My, the iPad must be powered-on and have an active WiFi or Cellular Network connection. As such, a “dead” iPad cannot be erased.
However, this situation is perhaps not as serious as you might think…
Your iPad has an encrypted file-system. All locally stored data is encrypted at rest - and cannot be accessed. The only copy of the encryption keys, that are required to access locally stored data, is securely locked away in the iPad’s dedicated security chip (i.e., the Secure Enclave).
To access the encryption keys, your iPad must a) be running - and (b) your iPad Passcode successfully entered; your Passcode unlocks the Secure Enclave - which in turn releases the encryption keys to the Operating System such that data can be decrypted.
Without your Passcode, your locally stored data will remain beyond reach. If the iPad cannot restart, the encryption keys can never be accessed by anyone. Given that the Passcode is known only to you - and the iPad is dead - all locally stored data is fully secure.
If you return your dead iPad to Apple, it will be responsibly dismantled and recycled.