Cannot boot from USB install (HP DV6)

I have installed Ubuntu (12.04 AND 14.04 separately, multiple times each) onto a 32Gb USB flash drive. The flash drive boots fine on a spare laptop (older HP DV7, windows 7), however on my HP DV6-6b04tx (windows 8) it hangs on an empty black screen (with back-light on) straight after my BIOS splash screen.

If I hold down the shift key on boot it gets stuck on a black screen with the text 'GRUB Loading.' and nothing else. These screens never change until I reboot. In both cases (empty black screen and loading Grub) the fan spins at max speed.

I have previously installed Ubuntu onto the internal SSD HDD and it booted fine, a live USB also boots fine. I am installing Ubuntu with a /boot partition and a separate partition for /, both ext2. I first attempted to create the root partition as encrypted however the same problem occurs with an unencrypted root partition.

I have updated the Grub config to remove quiet splash so that I would hopefully get some error output however this changed nothing (Still loads empty black screen/stuck on 'GRUB Loading.').

I found many people with similar issues on HP laptops with switchable graphics (ATI Raedon 6770m & Intel HD4000) so I followed some advice to load Grub in text mode, and to disable the ATI card (using vgaswictheroo) - again this changed nothing.

Any help would be greatly appreciated.

UPDATE: I have now also tried setting Grub config to use nomodeset and acpi_osi= , again no change

You will need to set up your USB boot device to boot in UEFI mode, unless you really want to reset your machine to compatibility mode each time you boot it. The USB will need an EFI partition (FAT32, 300M, flagged bootable) with the bootloaders grubx64.efi and shimx64.efi in /EFI/Boot, with the bootloader to run (shim for secure boot, grub for non-secure) renamed to bootx64.efi. You could have both boot mechanisms, like the live media does. You can just copy the bootloaders into the EFI filesystem if you want (or if the installer does not put them into the right place (and on removable media, that is likely, using the /EFI/ubuntu directory just like on the hard disk). Once you get grub running, then you will need to deal with any video problems. Some old UEFI machines with H2o may have problems with secure boot, but those issues in the Toshibas have been fixed 18 months ago, so always good to use the current firmware from the vendor.