Scantronic 9427 doesn't do anything?

I've just moved into a house with a scantronic 9427 panel but the user guide that has been left says 9448+ and 9448ES. I was left a user code and engineer code but neither do anything. Nor does 1234 or 0000. The top light and bottom light are continuously on. It doesn't beep at anything I do. How can I get it back to an operable position? Many thanks