That is the problem with laptops, after a bios update my fan sound like a chicken with a soar throat, really disturbing crap, removing the battery with charger plugged in and holding power button down for 20 seconds did squat for cmos resetting. However after a month irritation i didnt it use for a couple a months and presto it works like new now. This mean a complete drain of power is needed sometimes reset cmos. It may not need months but some serious downtime is needed for complete power drain.