Something does not add up. But i will debunk what is going on.

Seller says the hard disk that he got RETURNED from Buyer is



But buyer shows that this is the HDD that he got and returned is



Also the picture of Seller posted is 4.1GB. Clearly these isn't any 4.1GB HDD that has SATA interface. Ok Mr Seller let me tell you what happened. He did not change the board. But the HDD is defective by design. Read the link below.

https://forum.hddguru.com/viewtopic.php?t=11403&start=

So its a little misunderstanding. The hdd will fault if formatted with Seagate tool. What it does also upgrades the firmware. Which is beyond either Buyer or Seller control.

Under this circumstances since both parties already paid postage for returns, Seller should at least compensate 50% as good will. Why? Because i do not know neither Buyer or Seller is the one that used Seagate tools to format the hdd. If you look at it chronologically, the buyer would have used seagate tool to write zeroes to the hdd before selling. Which would explain why Buyer cannot detect the hdd because Seagate tools already upgraded it to defective firmware.

I won't be a part of this quarrel. But i can tell you what happened. So its now between the goodwill of the Seller and the discretion of the Buyer to agree on whats the next step.