boot - After Windows 10 upgrade I can no longer access BIOS

I posted a question recently regarding my Windows 10 upgrade which ended up with a black screen and cursor. QUESTION

I reverted back to Windows 8.1 using the "Revert to previous build" option in recovery, and all seems fine, except that Virtualisation is disabled.

I tried to open BIOS settings but it just boots into Windows. I've tried the usual F2 key and Shift F2, all the other F keys, tried pressing B and Shift+B but no luck.

I tried pressing the Lenovo key on the laptop when it is powered down, which shows a menu to either boot into BIOS, recovery, or show boot menu. I choose BIOS and it just boots into Windows.

I tried going into advanced startup options from Windows (Shift+Restart) and choosing "UEFI FIRMWARE SETTINGS" but it just reboots back into Windows.

Before the Windows 10 upgrade it was working perfectly.

Lenovo G580 laptop - Core i3 with Intel 4000 graphics. 8GB of RAM and a Crucial MX100 512GB SSD (replaced the original hard drive with this SSD).

Answer

This is a common problem in all Lenovo laptops. I also have faced this problem so many times. For solving this please go to the link(link of official Lenovo's support site) and download latest bios setup and install it. It will update your bios and all will be all right. Download bios set for window 8.1 and install it. The manual also is given in PDF format. http://support.lenovo.com/in/hi/products/laptops-and-netbooks/lenovo-g-series-laptops/lenovo-g580-notebook

Update:

After this again the same problem happens with me but this time I already have latest BIOS version installed in my system and the Lenovo don't allow the installation of same or lower version of the BIOS in existing latest BIOS. So I stuck there and can not do anything. I also approached to the Lenovo service center but they are also helpless they suggest me to change the motherboard which cost me around 10000 INR.