Z90DE7 Not booting from USB

Z90DE7 Not booting from USB

I have a, 

Dell Wyse - Z90DE7 - 16G FLASH 2G RAM - Dual Core

I have followed the:
USB_Firmware_Tool_1.20.0.1_Users_Guide_SEP2013.pdf -from WYSE

Downloaded the: Wyse USB Firmware Tool (87.5 MB) 1.20.0.1
Extracted to C:// drive

Downloaded Image BZB0_0858_8192.exe
Extracted Image to C:// drive

Run Firmware tool as Admin:

-Configure The USB key to to Copy/Pull or to update/Push Firmware
-Windows embedded standard 7
-Selected OS, BIOS, CMOS
-Unselect Preserve data partition
-Browse to the .rsp file ,open
-select USB
-Press next
-Press finished

Enable booting from USB in the Advance Menu.

Load USB into Think client -Restart
-press p till onetime boot menu pops up
-select USB drive

From there it does not boot ,tries to boot and goes straight back to the one time boot menu,
I have no clue why it is happening I have followed every instruction to a T
Tried another USB and boots but just get a black screen with one word saying GRUB

Tried Formatting the USB's first, before using the firmware tool.
1: 64GB Tumb Dive - Does not boot loads straight back to onetime boot menu.
2: 16GB Thumb Dive - Loads Grub.
3: 8 GB Thumb Drive - Does not do anything.

Any advice?