[Filament]

if anything I try with the method that passed @mothered which looks pretty good and functional

How are you going to be able to send the PS3 as manufacturer sent it? I don't think you'll be able to do mothered's method with your current situation. imo, it's easier to just do DNA and get new PS4 without sending PS3, or to try to get a used PS4 and claim used PS3 was sent. To be entirely honest, I think using the PS3 would make the SE less likely to succeed though. I personally would just repair and resell, or sell for parts.

Edit: reread mothered's post. Misinterpreted it at first. I misread it as sending a new PS3 box back lol
If PS3 doesn't fit well within the PS4 box, it can raise suspicion. Also, you'll have to be careful with the packaging, not to open it up too roughly. mothered's method personally scares me in that if the PS4 is sent to another person and they complain, it may be tracked back to you. I don't know enough about how Amazon handles return packages to back it up personally.

because I have a ps3 that doesn't work and I thought that instead of throwing it away it could be useful for a refund : )

In theory it sounds like a good idea however it simply won't work. I know a person that tried your exact idea and it failed miserably. Companies, including Amazon, aren't THAT stupid.

As mentioned above there's several better methods you can choose from.

Thanks for your comment. It's great to have data points on what works and what doesn't!