I am having trouble completing this tutorial with the expected results. I have two RPi 3s. I have completed the tutorial on one but find that this RPi will NOT boot without a microsd card. The tutorial notes that some will not boot unless there is a microsd but that the only content required on that card is bootcode.bin. This appears to be incorrect. Initially I created a card with the whole of the boot folder - this worked. I then (re)moved all files except bootcode.bin, cmdline.txt and config.txt - the RPi would no longer boot - I restored all files normally in /boot and the machine now boots. It does appear to be using files ONLY from the USB stick after boot.
The second RPi falls down at the start. No matter what, it refuses to change the result of the 'vcgencmd otp_dump | grep 17:' to anything other than '17:1020000a' I have no idea what this result signifies but the tutorial is quite specific that the usb boot will not work unless the result is '17:3020000a'.
Any information explaining the anomalies and solutions would be appreciated.