i can't boot parrot without USB ?

i have a problem of boot after successfully installed parrot, the problem is i can’t boot into parrot without USB.
i installed parrot with the given steps, one by one.
i found a Solution on boot in Ubuntu topic, but it missing something for working.
this is the solution tried :
sudo grub-install /dev/sdX

i should change the sdX to what ?
i hope someone help me to make parrot boot without USB and thanks in advance :face_holding_back_tears:

Use your EFI system partition. If you don’t have one, or don’t know if you have one, use /dev/sda1