Nothing.
Without the aid of the original owner/user of this iPad, you will never, EVER get this iPad to work for you.
No one here can help you and Apple will not help you, either.
This is a dead, useless device to you.
If you can, return this iPad and attempt to get your money back, if you can.
If no joy with a return and refund, please, recycle this device responsibly.
You'll never get this iPad to ever work for you.
Next time, If you need an iPad, then, you need to purchase a new iPad from Apple or a discounted, refurbished iPad from Apple’s Refurbished & Clearance section of Apple’s Website or a new or refurbished iPad from an Apple authorised, third party retail or online reseller OR other trusted sources for new or used Apple products.
If you must purchased used devices from unknown sources, untrusted sources, you must ask A WHOLE LOT more questions of the iOS device seller, and turn on the iPad to see if the initial iPad animated Welcome screen appears, that indicates a properly reset iPad, ask for more photo/images, ask if the iPad has user/iCloud activation lock and ask for photos/images/short video proof, ANY POSTIVE VISUAL PROOF, that such an iPad has been reset factory settings and shown proof of the iOS device's start up screen showing the animated, moving, multi-language “Hello” Welcome to iPad screen.
If the iOS device seller is unwilling to do all of this, pass on the iOS device and look at other iOS device sellers.
Sorry & Best of Luck to You!