Dead iPhone 6s maybe?

I have an Iphone 6s… I saw it charging, it was at 100% charge (I know, does not mean the battery is good). Two minutes later I picked it up and it’s dead. Nothing, nada. Not recognised by Itunes or any other program. My question is the following: I was thinking of buying a cheapish 6s with a cracked screen and just swapping it out with mine. But… how can I know if my screen is good?

(forgot to mention that I tried a fix with a new battery,,, did not work)

IO was thinking that a phone , unlike a computer, makes no sound when it boots up.. so if a screen has died, then one would get the same view as if the logic board tanked. But perhaps it not showing up on Itunes when I attempt to boot it up is the key that tells me it’s an internal problem and the screen is most likely good???