Can't get passed Failed to dump activation from device hackivating

Hello,

I just bought an iphone 4 off of ebay, and to get imessage to work, people say to downgrade to ios 8. I am trying to do that but i keep getting an error. Does it have something to do with the hactivation i completed or is it something else. (note: i made sure to update the ssl certificates)

https://preview.redd.it/i94dpa65f8ug1.jpg?width=2448&format=pjpg&auto=webp&s=31d4635596a678f69e64989f25e2e0d4660ec400