Screw for back cover of Galaxy Gear S2 SM-R735 watch

[stleusc]

So, I was smart and lost a screw for the back cover of my watch. I still have the other ones and I am unsure how to identify them to get some replacements.

The obvious places like eBay, Amazon all sell screws for similar models but I could not find anything for mine.

From what I can tell it is a Y0 head and without measuring, just from reading online it seems it is 3.5mm long.

Now with that, I know there are different thread sizes, etc. How would one go about determining all of that.
All without costing more than the value of the watch.

Do watch repair places usually carry an array of screws and they might just have what I need?

If not, how could I determine if the screws of a newer model watch would fit?
I see Samsung at least stuck to the Y0 head. But I assume that does NOT determine the diameter of the screw? Or the thread size?

But then again, from a business perspective, why change it for no reason? Same part, less cost!

Anyways, I was hoping someone here might be able to guide me in the right direction.

 

Thanks!