This is the purpose of an AED delivering a shock to the heart.
What is "restart a normal rhythm"?
You put your hands here to do compressions in CPR
What is "the center of the chest"?
This is the rate at which you should give chest compressions during CPR.
What is "100-120 compressions per minute"?
This is the type of surface that CPR should be given on.
What is "hard"?
If your parent is complaining of chest pains and shortness of breath and you believe he/she is having a heart attack, you should do this.
What is "call 911 and stay with them"?
Continue to administer CPR until one of these four things happens.
What is "the person starts to breath on their own", "an AED arrives", "emergency medical personnel arrive and take over", or "you are too exhausted to continue"?