Why iPhone 6s speaker doesnt work after replacing it?

I’ve got a 6S with broken screen and around 75% batter life with no working loudspeaker. I’ve managed to replace both the battery and the screen and everything works fine - earspeaker, microphon.. I’ve changed the speaker with new one, but it still doesnt work, no reaction at all, all the antenas are connected, the flex cable is ok but i can’t get it to work. Can i try something else or this is a motherboard issue.