There are certain devices that do do that, but it's not a defibrillator. A defibrillator will stop/prevent an arrhythmia by stopping the heart, and letting it restart on its own (hoping that it goes to a normal rhythm), and delivering further shocks if it gets back into one.
The device you're looking for to help a heart beat again would be a pacer, or a pacemaker, which will shock the heart to force it to pump, and restore rhythm that way. They're commonly used for conditions like heart failure, if the heartbeat generation systems/internal pacemaker can't generate a heartbeat quickly enough to sustain life.
Reddit's CEO outright admitted that their own app was "never profitable", while also complaining third party's apps were making money from the same content.
If I was an investor, I'd absolutely want a good explanation for why Reddit isn't able to make their own app profitable, while other Reddit apps can do just that.