Num Lock Blinking...

i have a computer here, i turned it on and the bios screen works, i checked how much memory was installed, looked at the hard drive, saw the drives i had, well, i changed the boot order because i wanted to reinstall the hard drive, come to find out that, the computer won't start, a little line like this, _ , just keeps blinking in the top left corner, and something else i saw, that is a first for me, num lock, light just kept blinking over and over, well, i did a little research about the light and all i found was, that it could be the cmos battery, so i went and bought one, replaced it, made sure it was in there, still same problem, i tried unplugging some of the DVD drives and still nothing, so now i'm a little lost, what should i do, any help is very much appreciative, thanks.