You need to put it in AP Fastboot mode, not just turn on debugging.
Power off the phone and then hold both volume buttons + the power button until you see the screen flash. Let go of the buttons and use the volume down button to scroll to AP Fastboot and then the volume up button to select it. Then use the utility to fastboot to .173
Well I want to fastboot back to .181... That's the one I'll be going back to correct? And thanks for your input.