Chosen Solution
I followed the full instructions from iFixit to remove most of the guts of my laptop in order to do a battery replacement, as described here: MacBook Pro 15" Retina Display Mid 2015 Battery Replacement Upon completion of the job, everything works except there is no sound whatsoever from the speakers. I get sound from the headphones just fine if I plug them in. If I unplug the headphones, the system preferences correctly sees that it should be feeding sound to the internal speakers (so it is not just stuck thinking it has headphones). Yet I get no sound whatsoever from either speaker. What should I check?
I think you just didn’t notice the headphone jack had failed or it just was the unlucky to break at the same time you where replacing the battery. Just the same check your speaker connections cables labeled Green and Orange here. Make sure the wires and the contacts are not damaged.
The jack is part of the logic board, sometimes the switch elements within it mess up
The contacts can rotate and/or dirt gets in the way. Use a toothpick to test them.
