[mothered]

I think he means why are they asking you to return it. Not the method of shipping I think

Correct.

Apologies, The reason is because they said they need their technicians to take a look at it and find the cause to the problem. They said they will send a new on when they receive it.

No problem whatsoever.

I realize you're not confident with boxing, but given the Item weight, the method Is Ideal.

First Class

If you're referring to First Class Couriers In Melbourne, Australia, they're a small company compared to the likes of CouriersPlease, so they shouldn't be too difficult to circumvent with boxing.