amherst

We just "inherited" a DVR unit in a premises where the occupant has left. We have its manual, although strangely no manufacturer is mentioned, just the model number "3924". We have the unit and 4 little cameras and connecting cables. We only seem to get two pictures when we connect the cameras. Channels 1 and 2 (the sockets on the unit) do not seem to work even when a camera is connected to them. Also, we do not have "administrator" access to the unit so we cannot do any configuration. Does anyone know a way to do a "factory reset" on this device? Thanks in advance for any help at all on this.....

Does no-one recognise this model, or know anything about who makes it, or how I can do a full reset on it? I have also taken a photo of the back of the unit:

Thanks for the reply! All the cameras work on channels 3 and 4. The problem seems to be with the unit itself. I can unplug the video cable from channel 3 and attach it to channel 1, but no picture appears on channel 1. The video leads connect to the back of the unit with BNC connectors, and then to the cameras with "phono" plugs. My main need is to find out what make this machine is, and then to get "admin" login. At the moment I only have a basic "operator" sign-on, so I cannot do anything with the set up. Anyone know who makes this device, or what a default signon is? Or how to do a total "factory reset"? All hints gratefully received!