iPad Activation Lock

I purchased a used iPad at our church rummage sale. Seems to work ok, but it wanted a passcode to log in. I connected to my computer and did a restore on it. When I tried setting it up, transferring data from my phone, it says "password required", because the original owner used Find My Phone linked to their Apple ID. The message says that I should contact the original owner but the previous owner is unknown.

What next?