factory restore ipad mini

Nothing.

Without the aid of the previous owner of that iPad, this iPad is a dead, useless device to you.

You will never, EVER get that iPad to work for you.

No one here can help you. Apple will not get involved and help you, either.

Attempt to return this iPad and get your money back or simply recycle this device responsibly.

You will never get this iPad to ever work.

Sorry.

If the device is Activation Locked, the lock must be removed before it can be re-used.

Here is more information form Apple about AppleID and how it may be disabled:

https://support.apple.com/en-gb/HT201441

If you are unable to contact the previous owner yourself, there is no way to trace them. Apple will not assist - and nobody here will be able to help you.

You can reset it. Try this guide:

https://support.apple.com/en-ca/HT211078

You may need to go to the Apple store however.