[GregAuRiz]

But how to prove a computer broken ? How to find the invoice? and how to convince SAV return an other article ?

Slow down - take one step at a time.

Firstly, claim the Item Is faulty and the next course of action, will be based on their response. Most likely they'll request the return, so you'd need to focus on circumventing that before anything else.

Is there any other reason than "dangerous article" ? And If they ask for an invoice?

[mothered]

Is there any other reason than "dangerous article" ?

If It's a laptop you're SEing, It's too big to box - tampering will be noticed at the collection point, so claiming It was disposed of for health and safety concerns Is the best option.

And If they ask for an invoice?

Use the corrupted file method.

[GregAuRiz]

Is there any other reason than "dangerous article" ?

If It's a laptop you're SEing, It's too big to box - tampering will be noticed at the collection point, so claiming It was disposed of for health and safety concerns Is the best option.

And If they ask for an invoice?

Use the corrupted file method.

And if I find a good S/N, do I need it to be close to home, or is it okay if it was purchased far away, and how do I know where it was purchased?

[mothered]

And if I find a good S/N, do I need it to be close to home, or is it okay if it was purchased far away

It doesn't matter, goods can be purchased and delivered from all over the globe.

and how do I know where it was purchased?

As an SE'er, It's your job to research It.