You should never flash in windows! Always in DOS, what you are going to need to do is clear the CMOS
Open your case and find the Clear CMOS pins, unplug your PSU from the wall and put a optical/hard drive IDE jumper on the pins and let it set for about a half hour. Then remove the jumper and plug your PSU back in and see if it will start
If not you have bricked your motherboard and will have to RMA it, unless you have a removable BIOS chip. Which I am not sure about in that board, what does your manual say?