No sound through earpiece or loud speaker on calls after changing scre

Would be awesome if someone could give me some idea here

I replaced my iphone 5s lcd screen and once i put it back together. the back cam never worked and there was no sound when calling out.

I tried to get sound by using headphones and speaker phone but i hear nothing, but the call goes through.

So i bought another 5s for parts and just swapped out the motherboards.

This did fix the camera issue thats resolved now, but I still cannot get any sound when in a normal call.

It works perfect on skype, facebook call ect no issues.

any help would be amazing

Nick.