The Mac now uses the external monitor as the primary monitor, keeping the laptop in shell mode.Keep the lid closed, press any key on the external keyboard to wake your MacBook / Pro from sleep.Put the machine to sleep and close the lid.Make sure the external keyboard, mouse, power adapter, and external monitor are connected to your MacBook, MacBook Air, or MacBook Pro.You can place your Mac in shell mode at any time using the hibernation mechanism, here’s how it works: How to use shell mode when waking your Mac from sleep mode
That’s it, as long as you have an external keyboard, mouse, and of course an external monitor to use your Mac, you’ll continue to use your Mac laptop in clamshell mode. If you want to boot your Mac directly into shell mode, follow these steps: How to activate shell mode on a Mac at system startup
