Screen wont work, even after replaced

so recently i got a case for my iPhone 5c and it was a screw on case, however i screwed it on a bit to tight and my screen had these yellow marks slowly show up. it was under the same pressure for about an hour and twenty minutes. (until the phones screen blackout out, everything else work such as music and siri) and still it was under pressure for about another three hours and i thought the screen broke so i replaced it but the new screen won't work either, i'm not sure if its the screens or the phone, please someone help