ELT probably sunk with the aircraft. Sigwx can confirm but as I understand it the ELT does not eject upon crash. One would think that by now they would but . . .

As for the fire I doubt it, if there was that much damage and the power busses were out there would be no auto pilot and probably no flight computer (it's fly by wire remember) anyway.Without power a 777 is basically a brick. I suppose it's possible (that only comms and other non essential power was cut) but IMO unlikely. Mind you the most recent heavies I have crewed were 707s and the occasional 727 so I'm not the most qualified here to answer that one.