Sounds like he's not able to pull up the boot menu?
Then have him change the boot order so it looks for a USB bootable first.
If he starts booting from USB only to have it go violet when you would expect the windows setup to start.
Then have him disconnect any additional monitors or extra devices from his video card/video out ports.
However, I've attempted to make a bootable USB drive in the past and I've never gotten a clear answer but from what I've read; not all USB drives can be made bootable. And some (mostly older) systems are very finicky about booting from USB.
Any chance you could make a bootable DVD? They are more reliable and predicable when comes to booting.