Nah, it's fair.

We've had to fry our failed HDDs because otherwise the vendor would replace them with those we've returned previously. Then they would not endure RAID rebuild and the cycle would repeat.

The fraud is theirs.

But you're supposed to hide the murder weapon.

Not keeping track of serial numbers?

Refurbished drives get their firmware and NVRAM overwritten. The subsequent units have different serial numbers and the labels get replaced.

Wow this is full dishonest if they are not marked as refurbished.

No, they do get marked as refurbished. That's why the serial numbers are different.

My original thought was they were threatening violence to the tech that came out

That was definitely my read. "Show them the instruments. That will elicit a confession!"

Fraud requires that there is some financial benefit to gain that you are not entitled to

IANAL but wikipedia says that you just need some sort of gain, not necessarily financial benefit. Warranty service entitles you to replacement only if it's broken, not when you feel like it. In that aspect you are gaining, since you're potentially getting a replacement you're not entitled to.

It's still shockingly wrong.

That's pretty punny.

Never did I consider that puns could be turned against me as well.