In the process of buying a 2009 MS 34 Trawler, which I believe was delivered with a now obsolete Garmin 720s GPS Chartplotter, and Garmin Radar (GMR 18HD??). Current owner knows little about the boat

. During survey we were unable to get the radar to work, or even have the Chartplotter show any available selections or screens for radar. I understand that supposedly the radar options are "Plug and Play" via an RG45 cable to the chartplotter, so perhaps the radar wasn't even powered, even though I had the RG45 cable plugged into the chartplotter.
Does anyone know "which breaker or switch" powers the factory radar unit?