[quasque]

The CMOS battery often has nothing to do with BIOS settings, on many modern laptops it's stored in the BIOS flash memory, with no such reset sequence available.

If properly secured, physical hacking is not as easy as it used to be.

[afhsfsfdsss88]

NVRAM can be overwritten with a factory fresh BIOS image....

[quasque]

Yes, but then you're in the realm of interfacing directly with the hardware to reflash the chip, somewhat upping the difficulty of this hack.