The Ctrl + Home combination helps you recover from a bad bios flash, but doesn't always work, so you still want to be careful about flashing the bios.
Check this thread for more information if you're interested:
Downgrade BIOS 209 from 217 then Laptop wont boot.There aren't any other special key combinations I'm aware of, but if you have more details about what you were thinking of, let us know. Thanks!