Chosen Solution
I found this apple watch series 4 40mm in perfect shape like new and I wonder if someone now why is like that and if you can finde the parts because it has four holes for screws.
This looks like an apple watch with the original 2 wrist buttons removed from the glass. i assume it means its been opened and tampered with possibly repaired. the location of those screws are odd though as in the IFIXIT tear down of the series 4, the screws would be facing towards the screen of the device and not the wrist.
I think you are seeing a second version of the back which is used on the Aluminum models Vs the Stainless Steel models. If you make your way to an Apple Store I’m sure you can get them to put the plates back on. I suspect they are press fit not screwed as the threads are to offer a grip for the plastic pin. Update (08/07/2019) Here’s a view of the black stainless steel model
