How can I fix my ADT system - loss of power?

My ADT system (made by Digital Security Corporation) goes off randomly. However, the control panel lights are off, no power to the panel. I've flipped the breaker, nothing, i removed the battery (thinking it could be shorted), nothing except then the system no longer randomly goes off. What should i check to get power back to the system. I found battery online but not sure if that would fix it. Also, there is a power-pack plugged in one of my outlets that goes to the system.