I had exactly the same problem last night. HP's 'Health Check' recommended that I flash the BIOS of our new HP Dv7-1175. Had the computer about 3 days, and was receiving some strange errors reporting unrecogized USB devices not recognized and a buggy USB driver. So, OK, Flash the BIOS.
Precisely the same thing occurred. The utility for flashing the BIOS ran, seemed to work, shut down the computer. Then nothing.
I restarted to a backlit screen, no POST or BOOT. Here's how I solved the problem (though I can't tell you why it worked, other than it obviously reset the CMOS).
1) Turned off the computer
2) Removed Battery and disconnected power cord.
3) Waited, pensively, for 5ish minutes (read several places to wait for 20 minutes; I didn't)
4) Plugged the power cord back in (I did NOT reinsert the battery)
5) Holding down the Insert/Scroll button, I held the power button down for 20-30 seconds. Nothing happened until I released the power button. When I released the power button (still holding the Insert/Scroll button depressed), the computer came up and Windows booted. Could not, at that point, get ESC pressed; wouldn't let me into the BIOS.
6) Restarted and prayed, came up normally; opened the BIOS by hitting ESC at the proper time, reset to defaults (just to be sure).
The computer has seemed to work operate normally since, though for the life of me, I can't tell you why this worked. I was, for the record, trying to press the Insert button, so if yours has these separated-- as my Toshiba does-- then I'd start with that.
Hope this helps someone.