Sorry the advice didn't help. When you start your computer, do you get the POST = white letters showing where you're going? That POST is not dependent of Windows, it's pure basic BIOS, and if you lack it, that would be a sign of a basic issue.
I think you may have some weird overrun of your laptop's monitor drivers. It may have been caused when installing the HDMI. It could be a registry issue too. What I would do is, to go to Safety Mode by pressing F8 at boot = right after the beep, uninstall monitor / graphics drivers, then reboot and go to F8 again, and re-install the ORIGINAL drivers you got with the computer. That way you get to point zero.
Another option is, take it to a Restoration Point, through F8. Choose a point "far...