What the GRUB? Installing a new OS when EFI won’t load

27 May 2026

Tags: computers; linux; operating system install; GRUB

The other day, I tried to open the Shudder app on our Fire TV, only to be frustrated when it didn’t load. After searching the internet for any suggestions (as one does), I learned that our Fire TV’s operating system was old. Like, real old. Certain apps, including HBO Max, no longer support older OS versions.

We bought the 55-inch television in December 2017, when it was on a mega holiday sale. Our Fire TV is a seventh generation, with the OS at 5.2.9.5. So... it will never update to the next major version.

It is a perfectly fine TV! We can watch live TV through our external digital antenna, and have no issues with any of the inputs. I set it up with a Sony stereo receiver, using the HDMI ARC, and all the devices run through the receiver. We use the Roku most of the time, since trying to detangle from the Amazon ecosystem, but there’s no VPN app for the Roku while there is one for the Fire TV.

What’s all that have to do with the title of this post?

I didn’t want to install the VPN on the router directly, but I have an old 2011 Mac Mini with an outdated version of Elementary OS, and thought I would install a new operating system and test it out with the TV. Zorin OS felt like a good option; I’ve used it before and the desktop is pretty customizable. But I ran into a snag.

I popped the bootable USB stick in, powered on the Mini, and quickly slammed my finger down on the opt key. Expecting the EFI boot menu, I got GRUB instead.

Now, I’m not uncomfortable using the command line, but I forget everything, everytime when using GRUB. I tried a few things, I read around Stackoverflow posts, and browsed some documentation, and figured out what I needed to do to get the USB stick booted up.

The whole chunk of commands to boot the stick through GRUB

If you’re reading this and just want the tl;dr, I’ll post the whole snippet, then run it through to explain how I got here. You might still want to read below, since paths may vary based on operating system.

set root=(hd0)
chainloader (hd0)/EFI/boot/grub64.efi
boot

Let’s break it down

The important thing we need to know is the name of the USB stick. Which disk is it? Typing ls -l lists all the disks and partitions with detailed information, and we’re looking for the one that is labelled with the operating system ISO. It will be something similar to this:

Partition hd0, msdos1: Filesystem type iso 9660...

Great! The USB stick is hd0.

The file that will boot the stick will be an .efi, and it will be somewhere within the EFI boot directory. It’s typically /efi/boot/grubx64.efi, but! The path we need will be case sensitive and we can’t just use this. There might be a different or simpler way to do this, but I just listed out the directories until I found the right one.

ls (hd0)/ got me to the EFI/ folder, all uppercase.
ls (hd0)/EFI/ got me to the boot/ folder, all lowercase.
ls (hd0)EFI/boot/ got me grubx64.efi, again all lowercase.

Awesome. We’ve got our disk and we’ve got our path to the EFI file. All this so we can make certain we have the correct items to set next.

First, let’s set the root to the USB stick instead of the computer’s hard drive, since this is where we want to boot from.

set root=(hd0)

Next, set the chainloader to the exact EFI that we are going to boot. This is the path to the EFI file we found above.

chainloader (hd0)/EFI/boot/grubx64.efi

Then, boot it up! This will restart the computer.

boot

When the computer starts now, it should pull up the “try or install” menu of the operating system on the USB stick. Select the option you want and get started using the OS on the stick.

References

Like I mentioned, I am not an expert with GRUB. Here are some of the links I used when figuring out this issue.

Questions or suggestions?

I dont have comments enabled on the blog, but you are more than welcome to message me on Mastodon! I would love any feedback you have on this method, especially if there are various ways to do this.