@upulasi_st3v3 @dmsosb (and bbspige too, but I can't figure out how to @ him\her): How long have you waited for without it starting up? Just asking because Aspire V5s, especially older ones, can sometimes take an extremely long time to turn on (my three-year-old V5-122P sometimes takes several minutes to start up), so, if you were waiting only a minute or so and then powered it back down, it's possible (although by no means certain or even probable) that it would have eventually started fully.

Several people here have said that Fast Boot completely disables keyboard interactions early in the boot sequence. This isn't actually true; the keyboard interactions are still there, it's just that, with Fast Boot, the early portion of the boot sequence is so fast that there's almost no time to press the keys to get into the BIOS. You basically have to know the right key ahead of time and start mashing it furiously the moment you press the power button, and even then it'll probably take a few times, but you should eventually manage to hit the key during that split-second window where it'll get you into the BIOS setup. Proof: I eventually managed to get into the BIOS of my Aspire V5-122P (yes, I know it's a slightly different model of Aspire V5 than the OP's, but Fast Boot works the same on all Windows 8/8.1 machines) using the built-in keyboard (I was trying to get into the BIOS to disable Secure Boot so I could install Ubuntu 16.10 alongside Windows; I didn't know at the time that Ubuntu has supported...