After replacing Audio (aux) port and charging dock, still no audio

Hello,

I can't listen to audio with the audio- aux port.

I thought it is because the charging dock part (which is also the aux- audio part).

So I replaced it, and it still doesn't work (but the charging has always worked).

1. Is it the only part responsible for the iphone earphones audio?

2. Is there a small part which might be lost? for example small part that is connected to this part, and isn't an integral part of the motherboard.

I also checked that the sound in accessibility settings is balanced, and also restored my iphone as new. So I don't think it's a software problem.