Cannot setup MATE, GRUB menu only

Support & Help Requests
1

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.

2

Hold down the F2 key and then power-on the computer.

3

Thanks. I’ve been looking for this solution for weeks.