I was given a used 360 and ran into the same problem, I couldn't find the power cable anywhere so I called Humminbird and they will send you the proper cable for about $42.00. The 360 you have isn't Mega, it hasn't been released yet and it won't be an Ethernet accessory. I've only had mine going a couple of weeks and already love it, takes a little time to interpret what it's showing but once you figure it out it's awesome.