Chosen Solution
I replaced my iPhone 6s Plus with a new one from iFixit. I followed all the instructions and everything works fine. However, when I get a phone call I can only hear it on speakerphone. Is there something wrong with a cable connection or did I mess something up?
It will have something to do with the top flex assembly. If you removed the screen while doing the battery change, check the top flex connector it is the one furthest down. Make sure it is seated properly.
