You need to connect the MacBook to a different Mac using a power delivery capable USB-C cable (USB 2.0 is fine so you can use the charging cable). Use to the left-front port to connect. When things are connected this way, the host Mac should give just enough power for the iBridge to boot up even if the battery is fully depleted or due to a firmware issue the Mac cannot charge at all. Then put the Mac into DFU mode and use Apple Configurator to restore the Mac. Until things are finished, you won't see anything on the MacBook, the screen won't power up so it will look dead, the only lifesign you get will be through the activity seen in the Apple Configuratior utility.