Putting Macbook into DFU mode

During the most recent upgrade, my MacBook seemed to freeze on the update so I restarted. Big mistake. After it came back up, I got the scary exclamation mark and text that linked to an Apple support page. The page gave me two options: ‘revive’ my Mac, or restore it. Reviving it meant connecting a USB-C cord between the dead laptop and a working one and then hitting a magic combination of keys on the dead one with the right timing to get it to boot into DFU mode so the firmward could be res...