WhatsApp recs / Calls on speakerphone doesn't hear me

Hello!

About 2 weeks ago my X fallen, and the OLED and the mic were messed up.

I replaced the screen with 89€, quite good price and the screen is like the original, but the Mic problem doesn’t fixed. I know that I need to buy another part of the phone and replace it. But I don’t know what’s the exactly part, if the loudspeaker (the small/light one on the top) or the speakerphone (the big and loud one at the bottom).

To report an example:

• if I try to do a WhatsApp registration it will just record like “straight white noise”
• during a call with I press the loud (speakerphone) button the other part won’t hear me, but with the regular call (with the standard not-loud loudspeaker) they can hear me.
  

Please, help me!

Really thank you in advance!