Okay so i tried to flash my xfx 6870 to the black edition bios, but i kept getting checksum error.I decided to force flash.Now when i try to boot nothing shows up at all on my screen.What should i do????
In this case, you have to boot from an old PCI(if you have a pci slot or use onboard video if you have it) card and then set the bios to boot from the pci card.
With that done(install your bad flashed card and leave the pci card connected to the screen), you can go and try to reflash the card. It is best to use the oldest non flashable PCI card you can(onboard video is also a good option if you have it).
With any luck, you can flash it back(i hope you backed up the card's bios first or else you will have to look for it online).
You will have to force for sure now.
Ensure you are using DOS(old windows 98 boot disk works great) if you are flashing in dos and not freedos or drdos. Those do not always work right for this.