XPS 8500, can't access BIOS via normal methods

Hello all,

I've got an XPS 8500 that I can't seem to access the BIOS on. When I power the machine on and see the Dell logo appear, I don't get any text or instructions for accessing BIOS.

I know with most machines BIOS is accessed by Esc, F1, F2, F8, F10, F12, Del, or Tab. I've tried them all, pressing continuously from the moment the power button is pressed up until Windows prompts me to login (about 10 seconds), and have had no response from anything except Tab. 

When I press Tab, I get a blue progress bar/timer under the Dell logo for about 5 seconds, and a text instruction that says "Press F12 for Boot Options", but nothing else. If I press F12, nothing happens. If I repeat that and spam F12 just like I would other keys to access BIOS, I still get nothing. 

At this point I'm suspecting:

• either post is too fast since I see no text instructions/miscellaneous loading information, copyright info, etc.
• or the keyboard I'm using isn't registering key presses fast enough or initializing soon enough

I previously used another keyboard and had no problems accessing the BIOS but no longer have that keyboard available to test with, nor another keyboard for that matter.

If I remember correctly, I did have to update my BIOS recently to version A12 for, I believe, compatibility with a graphics card upgrade I did. But again, I'm certain I was still able to access the BIOS previously without problems using the other keyboard.

I'm stumped. Aside from removing the CMOS battery, which I'm hesitant to do, I'm not sure there is any other way to force the BIOS prompt to appear with instructions on how to access it. I am using Windows 7 Home Premium so I don't have the Windows 8/10 advanced boot/BIOS options available to try.

Any thoughts or suggestions are appreciated!