If the PRAM reset fails, try reseating the video card to make sure that the PCI connections are not the issue (make sure to do a static discharge before handling the board).
Not a huge probability of success, but it's a 2 minute check that possibly could save the huge hassle of getting this fixed by Apple.
Not a huge probability of success, but it's a 2 minute check that possibly could save the huge hassle of getting this fixed by Apple.