Nobody has any ideas?
The power button must be held down for a 4 full seconds before it causes the system to be forcibly powered off. You want to hold the button down for 3 seconds; this will result in the full initialization of the BIOS and the presentation of the special boot/recovery menu. If you hold the button for too long, it simply powers off the system and you have to try again. It might take a try or two to get it to work but it should.
P.S. IMHO, for the tiny difference it makes in boot time, it's not worth it to enable any of the optimization parameters...