First, you should get away from BIOS flashing with the Windows @BIOS. I've done it myself but it's more reliable to flash with QFLASH.
The BIOS that you said has a black screen sounds corrupted if you can't delete key into it. I did that by not pulling the power plug and pressing the clear CMOS button once. It powered up when I pressed the button and messed it up. That was the 1 time I used @BIOS to fix it. Now I make sure to unplug when clearing the CMOS.
The only other thing I can think of is to use a PS/2 keyboard and see if that lets you in.
I'm no expert on RAID setups, I won't use them. But is sounds like you need to get both your BIOSes in order then re-install O/S. I don't think your motherboard is damaged just corrupted BIOS which can be reflashed.
How come you flashed F5 anyways, Gigabyte posted a F6 for your board?