Do you have a 4-pin motherboard speaker in your spare parts bin? I got a couple that came with cases and proved very handy. If you've got one, plug it in on the bottom right of the board where the FP headers are located (check the orientation, I think pin 1 is to the left, based on Asus' generic manual). Should anything beep, you can look it up in the manual's diagnostic section.
Have you done a manual reset of the CMOS settings? Unplug the power and use a screwdriver to short the CLRTC pins (bottom center) for a few seconds and see if that does anything.
If you did bork the BIOS update, you can still recover it: download a bios onto a usb flash drive formatted in Fat32 (that's important). Turn on the system, then plug in the drive to a usb port under the PS/2 ports. According to the manual this is supposed to work automatically even if the onboard BIOS has been corrupted. (If not, also try plugging in the drive before turning on the system). I'd leave out the system drive from all of your troubleshooting anyway, I'd rather see the "operating system not found" message after post than risk anything happening to the system drive.
Eating more cheese on Thursdays.