uefi - How to fix Boot Configuration Data (BCD) for Windows 8 EFI system

I have Lenovo H530 Desktop which comes with Windows 8. I tried to install Ubuntu on the system and ended up messing something on my way. Current status is my system won't boot into either one of them and will just fall into GRUB shell on startup. I have a 64-bit system with EFI.

^{Partition structure in GParted on Ubuntu live CD}

^{Partition structure in Windows 8 Repair command prompt}

I followed the instructions here as follows.

DISKPART
select disk 0
select vol 2 --> EFI
assign --> resulted in F: drive
select vol 3 --> Windows8_OS drive (471 GB)
assign --> resulted in G: drive
exit
cd /d F:\EFI\Microsoft\Boot\
bootrec /fixboot
ren BCD BCD.bak
bcdboot G:\Windows /l en-us /s f: /f ALL

Everything was success till here. But reboot still results in GRUB shell.

I have also tried following links

how-can-i-repair-the-windows-8-efi-bootloader

windows-7-suddenly-wont-boot-reboot-and-select-proper-boot-device-or-insert-boot-media-in-selected-boot-device-and-press-any-key-repairing-the-windows-7-bootloader/

but not much success. Any help to solve this would be really appreciated.

EDIT 1: bcdedit results in error
The boot configuration data store could not be opened.
The requested system device cannot be found