How can I get into debian to edit grub settings when grub is hidden and shift key does not bring up menu?

Question

I wanted to hide GRUB during boot, so that I can access the list of OS whenever I want to boot something other than the default. I hid GRUB by specifying in /etc/default/grub that

GRUB_TIMEOUT=0
GRUB_HIDDEN_TIMEOUT=0
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_DEFAULT=0

The problem is now that whenever I press the shift key duing boot, Loading grub is printed , but then quickly thereafter loads the OS without giving me an option to select OS.

Question

Now that I cannot get into grub using the shift key, how can I get into debian to change the settings?

Answer 1

You can boot your system from a Debian installation disk, choosing the Rescue option.

From there, you should be asked if you want to to open a shell on your original Debian file system, so you can edit /etc/default/grub file and then run update-grub.