I have the latest distro. of Ubuntu and a Toshiba Satellite laptop.
I’ve already searched for the default keys to access the BIOS, (F2, F12,
holding ESC) and had no luck.
To describe what happens when I push the power button, the screen
flickers black for a half-second with a cursor at the top left, then
immediately goes into GRUB menu regardless of what buttons I press.
It will continue to boot Ubuntu normally. I have no Windows versions installed on hard disk, or anywhere else.