Have you tried changing the vga cable to the onboard vga connector after the reset bios occurred? I have spent the last 2 days in a dilemna such as yours. Anyways if possible remove the discrete graphics card, then reset the bios again and swith the vga connector to the one which is on-board. At this stage you should be able to go into the bios after turning on the PC.
Now you need to choose the on-board graphics as the primary and the only display that the bios should boot. Save and exit the BIOS and restart, build a recovery usb with the backed up bios of the graphic card in it. Shutdown and re-insert the graphics card and turn the PC back up at this time you should have display through your on-board card. Try and run the commands and see of it helps, It didn't help me because nvflash would not detect the presence of my GPU!
Anyways i wish that nvflash does detect it for you!
*runs off to looking for a graphic card