I am answering this question in hope that it will help someone else in the Future.
Usually you are right in trying to get to Grub with Shift! But Grub usually explicitly prohibits using the Shift key if you have "Fastboot" enabled:
if [ "\${fastboot}" = "1" ]; then
# timeout_style=menu + timeout=0 avoids the countdown code keypress check
set timeout_style=menu
set timeout=0
Taken from /etc/grub.d/12_menu_auto_hide
But the other people who answered in here are right aswell, but I think for a different problem. If the Grub menu does not start automatically on start up, you can try fiddeling with your /etc/default/grub file.
Open it with sudo rights:
sudo nano /etc/default/grub
And there you should see two entries of importance to us:
GRUB_TIMEOUT= "some number, probably 0 or 5"
GRUB_TIMEOUT_STYLE= hidden/menu/countdown
GRUB_TIMEOUT tells us how long Grub will wait for Input until it loads the default OS.
- 0 will instantly choose the default OS
- -1 will wait on user input indefinitely
GRUB_TIMEOUT_STYLE tells you how the Grub menu is shown, if at all
- hidden= Hides grub unless you press Shift in time
- menu= Will show Grub
- countdown= Will not show grub, but an actual Countdown
on screen
Hope that helped
(more info on the other entries in /etc/default/grub Ubuntu Wiki
Esc
key after the BIOS splash screen worked for me. Pressing earlier would land me to CSM screen (since I have disabled Secure boot). I can just suggest timing.