repair - earpods entry doesn't work

Hello, I have a problem with my xiaomi mi4.

I have tried all the earpods type possible: apple, Samsung, xiaomi piston 3, and I have always the same problem: I can hear the music but the mic and the bottoms of the earpods don't work. I also tried all these earpods on other phones and they work properly so I know that the problem is in the phone. I once changed the phone display. What are your suggestions? Could I misplaced the hardware part of the earpods' entry during the reassembling process? Or is it probably just broken? And in the last case where can I find the replacing part?