I got a used iphone and went and tried to update and restore it, but it said it couldn t because of an unknown error. What do I do now?

I got a used iphone and went and tried to update and restore it, but it said it couldn t because of an unknown error. What do I do now?

You didn't exactly state the error. You could try again & see what happens. If it doesn't work out you should try to get a refund.