Pressing F2 (setup) just gives me a black screen. Tried pressing F12 (boot options), same result. I did see a small blue progress bar when I pressed it but same result, a black screen.
To recap, I'm able to run Dell's ePSA diagnostics (Enhanced Pre-Boot System Assessment) by pressing the Fn key simultaneously with the power button. All hardware checks pass. I've removed and reseated all components that I'm able to access, I.e., battery, hard drive, wireless card, keyboard, and the CMOS battery. Since I was able to remove the HDD, I copied over my important files to my desktop but I really want to use my laptop again. I've contacted Dell and one of their technical "wizards" suggested that I shouldn't be using Win 10 yet since it wasn't officially released (guess he never heard of the Technical Preview), and that I should uninstall it and reinstall my previous OS. Words escape me so I'll just leave it at that.