[mothered]

I was thinking broken item returned in the original box that the new order came in, but that might make it even more obvious that the serial on the box and the serial on a camera, for example, don't match. Do you think that's likely on an expensive return?

Alternatively, you can opt for the sealed box method, by purchasing your Item from the company you'll be SEing and replacing It with anything of equal weight.

Provided there's no signs of Inconsistences/tampering with the box/packaging, It has a very high success rate.

I guess it makes the most sense to act like any normal consumer would. Something came broken, so I sent it back, no more thought would be put into it than that.

Correct.

Plead Ignorance and treat the SE as a legit claim, yet manipulate It to your advantage as needed- without raising suspicion.