option-grub, the command shown below would look for grub in /dev/sda the typical location, if you know grub to be placed elsewhere then change the command below to suit, ie: /dev/sdb etc, if grub is located as expected the output should include GRUB ,the "To View/Share" instructions are here..
( sudo dd bs=512 count=1 if=/dev/sda 2>/dev/null | strings ; [ -d /sys/firmware/efi ] ; echo "EFI boot on HDD" || echo "Legacy boot on HDD" ) > ~/trouble-shoot-history.txt ; echo "Done, the log has been saved to ~/trouble-shoot-history.txt"