On the Acer Aspire V5 series, if you open the bottom cover and remove the RAM you should find a couple of pads on the board labelled G2201. Remove the battery and power cord from your machine. Use a piece of wire to short those two pads. While holding the wire, plug the machine back in, then hit the power button. This should clear the password. I had to do this a number of times, but what finally worked was to hold the power button down while the machine came on, then shut off. I cycled this a few times then eventually the password was removed and I was able to get into the BIOS setting screens. Good luck!