My iPhone 6 headphone jack wasn't working properly, so I decided to purchase the replacement part from iFixit, which also included a new lightning port, speaker and a few new connectors for other components.
I followed the instructions correctly, however, the speaker stopped working, and the vibrator would work only occasionally (original vibrator that came with the phone, but new connector). The whole phone would get very hot just from being switched on, and also had poorer battery life. Wifi would also drop in and out, probably because of the new cable/ connector for the antenna. None of these issues were occurring before I used the replacement part. I ended up having to go to a repair shop to get a full unit replacement done. See photo for the replacement part.