as a preface - my only experience with Ubuntu is playing around on VM's, so I apologize in advance for any naivety.
I've just updated my Yoga 2 Pro from Windows 8.1 to 10, and am trying to install Ubuntu 14.04.2 along side. I created a UEFI bootable USB with Ubuntu 14.04.2 using rufus as described.
I disabled secure boot and fast boot and enabled USB boot in the BIOS menu. I was able to get 'try Ubuntu' running, but when I go to install, I get errors with the grub install.
When I select /dev/sda as the pointer for the boot loader, I get the error:
The 'grub-efi-amd64-signed' package failed to install into /target/. Without the GRUB boot loader, the installed system will not boot.
This is followed by the installation crashing.
Looking online, it seems like others had this issue, but it was resolved when they pointed the boot loader to /dev/sda2 (which is where the Windows Boot Manager is). Unfortunately, I get another error when I do this:
Executing 'grub-install /dev/sda2' failed. This is a fatal error.
If it matters, I elected to not have separate root and home partitions due to a smaller SSD. So I have a partition, sda8, that is a 8gb swap partition and a ~25gb root partition, sda9, formated in Ext4 and mounted at /.
EDIT: I've tried going through the suggested steps to no avail. I tried to install 15.04 as well (the above link seems to indicate that alone could resolve some UEFI related issues) but got the same errors. Ubuntu seems to be installing (the installer sees a previous install in the correct partition), but crashes at the boot loader.
EDIT 2 - SOLUTION: I'm not sure what solved it, but here is what I did in case anyone else has the same issue. Some how the EFI partition corrupted. I deleted the ubuntu partitions using a live USB, then deleted /EFI/boot/Ubuntu. This lead to a failure to boot windows as well, so I used a windows recovery USB to repair windows boot manager. Then, in windows, I created the partitions for a clean ubuntu install. Finally, I reinstalled with no problem.
