element

An hour after I installed the 8th camera on my mux16tc multiplexer, the unit froze up completely. I reset the power and now all it does is beep continuously when plugged in, no system check, cams or no cams. Thinking the unit was just used up, I plugged in an identical multiplexer backup only to have the exact same thing happen after 30 minutes. Any ideas why this would happen? Logic says something with the new camera, but when I plug in each camera to test individually to a monitor they all seem fine. Now I am scared to try a quad backup or new dvr until I have more answers..