Most bios flashes will reset the bios to it's default settings once flashed, and so right after the pc reboots the first time you need to hit the delete key (most common, some pc's hit F1) to get into the bios and make adjustments so it reflects your former setup. Turn off the pc and turn it back on, hit the delete key as soon as you see something appear on the screen and this should get you into the bios.
That's where I would start first, its probable that default settings has changed some hardware setting so linux can not boot.
Would it be ok to revert back to the previous version of my BIOS? I've heard that's risky, as it's flashed onto the chip, and can damage it.