R7800 bricked, how to unbrick?

R7800, purchased used, arrived in an unaccessible state.  When you plug it into power, the power immidietly comes up solid orange, and the internet light comes up solid white.  The LAN's blink in sequence white, then that is it, router stays that way.  Power button has no effect on anything, you push off and the lights remain solid.  LED switch works.  Plugging devices into the LAN ports prompts steady LED on but nothing else.  Router is seen as an unkown network, but cannot be connected to by my PC, and is not broadcasting WiFi signal.  Holding in the reset button for 10 or 30 seconds has no effect.  Plugging in the power wiht the rest button pressed also makes no diffference.  WiFi and WPS buttons do nothing.  Is there any way to force firmware back into this brick, or if the reset process cannot be accomplished is this just a heap of steaming trash at this point?

Paul