The software for the TiVoHD? The NZ/Au software is very different from the US version.
I have an image online if you want the link to restore your TiVoHD with WinMFS.
Since you have two TiVoHD you could just swap the HDDs which would quickly tell you if that was the problem.
Have you tested the component or composite video outputs?
At least you have a power LED. Do you see the orange LED flash when you press the remote?