Assuming we dig up some UAP inside of a large, deep cave. The material cannot be identified. What is the scientific approach to research and reverse engineer the material?
In physics, you'd start with a mass spectrometer which would quickly tell you what the elemental composition was, along with more detail. Then more refined GCMS and other forms of mass spec, as well as some X-rays at your local synchrotron, will give you some more structural information. There's also neutrons and a few other things.
If you ground up your UAP and what came out wasn't at all analyzable with a mass spec ,xray spec, or neutrons, then you'd have armies of otherwise bored research scientists asking to try every single method. IE, if you find unobtanium, everybody will want to obtain your unobtainium.