Unable to access BIOS menu after installing Windows 8

Solution 1:

You should be able to dual boot.

Did you leave fast boot in UEFI on. That often is the major issue, as booting Windows is required to be fast per Microsoft. And then vendors rely on Windows menu entry to get into UEFI. But when Windows does not work?

And did you leave fast startup in Windows on?

You may be able to directly get into UEFI with full power down or cold boot. If laptop remove battery. And hold power switch for 10 sec or so to drain any left over power. Then boot and immediately press correct key to get into UEFI.

Others have had to go one step further and short jumper pins on motherboard.

Grub also now has a boot entry, usually last one. Menu entry: 'System setup' which uses this entry in grub -

fwsetup

Reboot into UEFI:

sudo systemctl reboot --firmware
sudo systemctl reboot --firmware-setup