the loud crackling in from blocked speaker .... sound can't exit so the sound is bouncing off of clogged mesh..... all you have to do is change the mesh that the speaker is facing and its fixed. I changed the speaker but noticed when i tried to make a call it echoed but when i had the phone open and speaker slightly slanted not pushed down it sounded clear so i checked the mesh and it was clogged and full of filth after that it sounded clear.
Change the mesh or remove the mesh and test connection this isn't hard ware lol this is simple clogged mesh that sound cannot escape
Pedro - iTechiie Solutions