14.04 - GRUB not installed correctly by ubuntu server manual process?

symptom:
can not boot from SSD after installing ubuntu server 14.04. BIOS menu keeps returning back. No dual booting.

setup:

• Lenovo T430s with windows 8 preinstalled.


• BIOS boot menu supports both legacy and UEFI.


• created GPT with gparted. /dev/sda2 is where i installed ubuntu. /dev/sda6 FAT32 is the EFI system partition.


• /dev/sda6 has flag boot and esp set (set from ubuntu install image).


• i installed server image following the "manual" option. when it asked where to install grub, i specified /dev/sda6. no error.


• successful install.

diagnoses:
I mounted both /dev/sda2 and /dev/sda6 on gparted live CD terminal. it turns out /dev/sda6 has nothing in it. Why? and how do i fix it? Thanks!

It turns out I booted the installer into the BIOS mode. See this article.

I tried to boot the installer into UEFI mode on that lenovo but the screen flashed once and then it just halted.

I tried to use the same live USB on another PC and it installed ubuntu to UEFI mode just fine. So there is something wonky with that Lenovo.