R720 Stuck after CPLD

I have a Dell R720, that I have taken down to minimal specs and it's not allowing me boot into bios or anything else. The keyboard works up until the post is done, and once I try to hit F2 or anything else the num lock goes off and the server no longer accepts keystrokes. I can hold the power button down, shut if off and back on, only to get the same result. I have tried different keyboards, different USB ports, monitor plugged into the front and back and not plugged in at all and always the same result. 

I have seen one or two other post about this issue, and have yet to resolve it. Is there a way I can use the console port on the back to see what the server is doing and where/why it's locking up? Also an odd part is that the cursor keeps flashing at the bottom once it has stopped accepting keyboard strokes. 

I know the bios is out of date, but I have no way of updating it now as the machine won't get past POST. Does anyone have any idea what would cause it to hang like this? Is there a fix for it? I'd rather not have to buy a new system board. 

Any thoughts or things I could try I should be able to accomplish and test. Thanks in advance!