Just to verify, you tried changing the charging p***ort***, right? That's the lightning connector assembly that comes with a new headphone jack; that's what you replaced, is that correct?
There is a contact inside the headphone jack that switches between headphones and the speaker and if that is damaged or jammed, that would be my first guess as to the cause, but if you've already replaced it with no change then you're looking at either a connector issue on the motherboard or other kinds of problems as described by @tzfadly.