When re-attaching the speaker connector, also pay special attention to pushing down firmly on this to ensure a connection is made. Again, not too hard, but it is easy to push down enough to think it is connected but it can easily not be.
Very straightforward replacement.
Take special care when removing the microphone and speaker connectors from their respective sockets. Just be gentle and methodical.
Ensure you press down firmly, but not hard, after microphone replacement when reconnecting the battery connector to the motherboard.