Hello! I’m not the most intelligent when it comes to Linux, so I might just be overlooking something obvious here. But whenever I try to boot into Ubuntu Mate after the installation, it gives me an error on the bios, I go into the boot manager and whenever I try to boot from the internal storage I have it installed on, it gives the same error issue.
Failed to open \EFI\BOOT\grubx64.efi - not found.
Failed to load image \EFI\BOOT\grubx64.efi - not found
start_image() returned Not Found
I ran the installation again and watch the terminal and things seems to install correctly, even grub. Am I missing something here?
Chromebook’s use a custom made bootloader, and grub only installs on an Efi System Partition. After a quick search, it looks like it can be quite a pain to completely remove ChromeOS and replace it with Linux (from what I can tell).
After searching, the following seems to give instructions on how to completely replace ChromeOS with Linux. There might be someone on here who has installed Ubuntu-Mate (or any other Linux distro) onto a Chromebook that could give you a little more help. 
I have already completely uninstalled Chrome OS, and installed Windows 10 in the past. Though, many drivers were missing, and I’d rather use Ubuntu Mate anyhow.
A small update:
I kinda fixed the error with grub, and Ubuntu Mate seemed to install properly to the internal storage. Unfortunately now, whenever I try to boot to the eMMC storage, it will not boot, it returns me to the UEFI/BIOS. Wheneer I attempt to boot up the computer, it takes me straight to the startup.nsh.
Any ideas?