Double check fuses with a multimeter. Swap the PCM relay with its neighbor. The CPS will not cause complete power failure - something got the feed to the PCM - whether that is a shorted wire, fuse, or relay is what you're going to have to be digging for. Hopefully it wasn't the PCM itself - more likely one of the causes listed above. The fuel heater shorting would take out one of the feeds to the PCM - your WTS light would be out but it shouldn't have affected everything on the instrument panel. Don't forget the fuses under the hood.