Let the secret be revealed unto you. Warning: This will format the hard drive on a PVR.
If you are booting up an Entone Kamai 450 or Amulet 455m sometimes the Menu option does not come up. You likely want to get into the Menu before boot up to tell the STB to either boot via Coax or Ethernet or both.
While it is turned on get a paper clip and press the reset button on the bottom of the STB until the screen goes black. Upon the next boot you will get the prompt to hit Menu to select the interface.