Kindles can be blacklisted without being stolen for various reasons.
Jailbreak can't be done on later FW or on later kindles that don't boot.
The registration is involving an account at Amazon, so jailbreaking can't undo blacklisting, just enable some functionality.
Likely the Scribe was faulty and Amazon supplied a warranty replacement and blacklisted original to save return cost.
The seller told you it was stuck, so you made an assumption and wasted your money.
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