new iPhone 6s plus, upgrading from iOS 9.0.2 to 9.2

bought a new iPhone 6s, tried to restore backup from old iPhone 6, it said sorry, your version isn't up to date, so I tried to update it from iOS 9.0.2 to 9.2, every single time it says it is unable to download due to error (it wasn't very specific).

Please help! very annoyed and impatient 😢