Some people suggest that the glue that holds the golden wires to the cones starts to dry/crack, which causes it to rattle. You can use silicone or glue to hold the glue that is on there down, and the rattling should stop. If this makes you nervous, adjusting the golden wires by moving them around can also seem to fix the issue, which is a lot easier.
Big points to this one, especially for mentioning needing to plug the laptop in. The bottom case needs to be screwed in and laptop needs to be plugged in before it will boot.
