Normally if you mod the bios you void the warrenty (I think). However, if the un-modded bios also doesn't work either the card is just bad (or you OC'd it too much).
It was overclocked to 2250MHz, but it was running fine for a month OC'd, and it was running fine for a week with the modded bios and OC'd. Temperature was also below 60.
.Maybe someone can explain how the warranty providers find out about the BIOS mod?