So I had a random thought earlier. At one point, the cessation of the heartbeat signified death. But now we have CPR. Now 'brain death' is often considered to s

So I had a random thought earlier. At one point, the cessation of the heartbeat signified death. But now we have CPR. Now 'brain death' is often considered to signify death.. but could/can we 'restart' the brain as we do the heartbeat with CPR?