How to install Ubuntu using the efi shell

Ubuntu uses grub-efi for UEFI systems. So what you really want to load from EFI shell is GRUB.

This should be EFI/grub/grubx64.efi

Type mount for detected storage devices:

mount

This will only tell you basic information about PCI bus location bus type (SATA), device type (HD, usb etc) and partition type (GPT). Try to guess your disk. If you get it wrong thats okay you'll confirm in the next step.

mount blk1
fs0:
ls

That mounts the file system of the first devices first partition and prints the files. The file list should contain "EFI" if it does proceed otherwise try other blks.

Try

ls EFI\grub

and confirm grub is present. Sometimes its incorrectly in BOOT.

ls EFI\Boot

and check for grubx64.efi

Once you've found the file simply start it.

EFI\grub\grubx64.efi

Press enter. If you have secure boot then you should be looking for the file shim.efi and do the same thing. Otherwise you'll need to add grubx64.efi to the allowed executables in SecureBoot.