Bought a phone paid off fully but when trying to unlock it I cant

How do you know it doesn’t have a balance?  If you bought it from a third party online, it could be a used phone and there was a previous owner before you who didn’t pay.

On Amazon it was listed as new, I paid $1k for it. I'd imagine it wasn't linked to anyone's account

Return it.  Amazon ads are not always correct.  Buy the US unlocked version, it will work just as well

Hi @WolfeUnsworn,  

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They can list it however they want on Amazon.  It might even be new in the box instead of being resealed, but you don’t know the history of the phone.  Someone who bought the phone from AT&T may have never used it, sold it to the Amazon seller for quick cash, and skipped out on making the payments.