You need to disable secure boot first. Volume up then power button, then disable secure boot save and exit.
To boot to usb you use volume down then power button. It will see your usb or dvd drive and then boot to it.
I just did this to my surface pro to make an image.
To boot to usb you use volume down then power button. It will see your usb or dvd drive and then boot to it.
I just did this to my surface pro to make an image.