But it is none of those.

Are faulty, or become faulty within a reasonable period of time after purchase

They are not faulty it is a Beanie Kid Teddy bear. Brand New

Are not fit for any purpose you stated or that the buyer made known to you

It has no purpose other than for a child to cuddle or as a collectable.

Don’t match your description or sample

It is 100% exactly as described and as seen in photos.

Are of unacceptable quality,

It is perfect quality. In shop purchased condition

Fail to meet other mandatory consumer guarantees under the Australian Consumer Law.

Meets all laws as far as I know as they are sold in shops as is.

So none of these are reason to refund the buyer.