Iphone 4 screen replacement? - 1

I have two iphone 4s. One will not read sim card anymore but is in great condition. The other works fine but has a shattered screen. Could i take the screen from the one that will not read sims and put it in the one that needs it? Or take the mother board from the one with the busted screen and put it in the one that will not read sims?

You could, but its very hard to do and you will probably do more damage than good.