I needed to downgrade from 18.04 to 16.04 in order to make use of Intel's OpenCL. I put Ubuntu 16.04 on a USB and configured the USB with the "Startup Disk Creator" tool. I booted my Lenovo Thinkpad T470s laptop using the installation media, and all went fine until it needed to shut down and restart to complete the installation. I got a black screen with some white text telling me that the core temperatures were too high. I powered down the laptop, and then when I booted again, I was brought to the BIOS "choose startup device" menu. I selected the recently installed Ubuntu option, but the screen just flashed and went back to the selection menu.
I tried to boot from the (same) USB again, and reformatted it first this time, to see if I could just re-install in a colder area, but I got this very strange message:
Failed to open \EFI\BOOT\mmx64.efi - Not Found Failed to load image
\EFI\BOOT\mmx64.efi: Not Found Failed to start MokManager: Not Found
Something has gone seriously wrong: import_mok_state() failed: Not Found
It should be looking for the grub EFI file, shouldn't it? I have tried wiping the USB and putting the image back on with the startup creator, but I get the same error.
Under EFI/BOOT/ on USB device, I have the following files: BOOTx64.EFI and grubx64.efi. I have tried copying the grubx64.efi file and renaming it with the "mmx64.efi" name it's looking for, but I am unable to paste anything into the device. I suspect that the USB device got set to read-only after the disk startup utility completed. In which case, how could I set it to write? I have tried adjusting the permissions by right-clicking in the file explorer and going into properties, but it won't let me change it to allow write permissions. Is there a way to force this by issuing commands in a shell?
Has something gone wrong with the bootloader in my laptop's hardware? How can I repair it?
