Remember this Terminal command:
sudo pmset -a lidwake 0Andy Ihnatko explains why:
It’s a safety thing. Way, way too frequently I’ve picked up my laptop bag and it felt…warm. I unzipped it and heard a screaming fan. At some unguessable point in the recent past, the MacBook got jostled just enough to twitch the screen sensor and it woke up.
Inside a sealed bag whose thick padding acted as thermal insulation. Result: a white-hot $1500 computer. That can’t be good. If there are any weak points in the hardware, that sort of abuse will cook ‘em right into a hardware failure.