Enable MacOS Start Up sound in the new 2016 and 2017 Macbook pro
Disable boot on power source and boot on lid open by running this on terminal: sudo nvram AutoBoot= Enable it again by running sudo nvram AutoBoot=%03 Feature removed by apple on latest firmware, doesn't work anymore. Bonus: Boot chime control sudo nvram BootAudio= sudo nvram BootAudio =%01