@bloodwar I have looked through the code up and down, forth and back… Just don’t know all about UEFI and have no idea why this goes wrong. I am pretty close to sending a message to the kernel mailinglist. But before that I’d like you to try other kernels first. Please use some older kernels just to see if those can boot on that device. I think the easiest way is to download old kernel binaries here and here, plugin the USB key you made and put the kernel binary on it as EFI/BOOT/BOOTX64.EFI (rename that file - GRUB EFI binary).
Now boot the Lenovo N24 off that USB key and see how far you get. If you see Kernel Panic - not syncing: VFS: Unable to mount root fs on unknown-block(1,0)) than you are past the issue. If it just sits there for 3 minutes then I’d expect it to be locked. Please try at least 10 kernel binaries of various versions from the links above.