Revive the apparently dead

My MacBook Pro 16-inch M1 Pro shows no signs of life after I upgraded its macOS. Has it died?

- by JESSICA JAMES

Maybe not, as it could be in DFU mode waiting for its firmware to be restored. If that upgrade went wrong and failed to update the firmware properly, it will be unable to start up beyond its Boot ROM. It’s then designed to run just the early stages of startup, enter DFU mode and await connection by another Mac to rescue it