Question- are you dual booting any other OS's (Windows, another distro) or is Mint the only thing on your computer?
If grub only detects one OS, then it will hide the Grub menu regardless of the 'hidden' setting.
To check your grub settings on this, navigate to /etc/default/ and open the file called grub (it will open read only this way)
One of the lines (probably the second) will read
- Code: Select all
With the '#' at the front it means the line is commented out and is ignored.
With the '#' the grub menu is set to display
Without the '#' the grub menu is set to not show for the amount of time specified (0 is no delay)
If you only have mint you'll probably find that the menu is actually set to show- I believe that is the default.
Let me know if this is not the case