Hello, I’m Nathan, and I’ll be assisting you today. My livelihood depends on your positive feedback, so your satisfaction is my highest priority.
Sorry to hear you’re having trouble.
The prior owner doesn't need to know the wifi password ***** previously on the kindle.
You only need to know your own wifi password, to get it onto your home network.
Now if you're referring to an amazon account/registration password, or a security/lock password (to turn it on) that is entirely different.
You will need to first get the kindle online (linked to your own wifi) and then registered to your own amazon account.
Please clarify which of these you need help with.