Doing CPR in the wilderness is futile. I would, however, make an attempt to open the airway and perhaps give several ventilations. You may be dealing with respiratory arrest and a little mouth to mouth could be lifesaving. You are partially correct. The most common cause of cardiac arrest is VF and this cannot be converted with CPR alone.
Electricity is required.
However there are some instances when the heart is going very slowly and CPR can oxygenate the system enough to get the heart going again. Also there are instances when the person is really in respiratory arrest and the heartbeat is too faint to feel. In this situation CPR may be enough to get the heart beating stronger.