Quoted from Anony:Sellers should be required to indicate which user bought the machine so that user can be authorized to leave feedback. I'm sure scammers like this would just game the system but they could be restricted from selling for constantly saying "someone off site bought it" when it's not true. It would be really easy for the OP to prove he bought the machine since he now has it in his possession and can take pics to prove it.
I know several other marketplaces that ask you who you sold it to when you mark the item as sold and they usually use who you've been messaging as the list of options.
No need to put extra rules in place, I feel bad for the op but they didn't ask for better pictures in decent lighting or inspect it properly when dropped off. I have done some similar things when buying games but blamed myself for not being more diligent and just moved on.