I just tested how to recover from a bad flash, and I may have a couple more things to try that worked for me.
As mentioned above, place a working card in the first PCIe slot, and the bricked card in the 2nd.
Now boot into safe mode. Open up the device manager and uninstall the video card drivers so it shows nothing under displays.
Boot up into windows, and then perform a flash as described above (atiwinflash -f -p 1 correctbios.bin).
You can find the bios here, most likely: http://www.techpowerup.com/vgabios/