[Matt Devo]

 Yes, I did try all 3 of the free ports.  No success.  

I just tried removed the USB keyboard and the Chromebox didn't show the ESC prompt?  It just booted straight into Kodi.

What should we try next?

UPDATE:

I tried some more things.  All 4 USB ports were empty, I even removed the keyboard.  I rebooted by unplugging the power cable.  Here's what I tried:

• Formatting a USB stick in exFAT = FAIL
  
• Formatting a USB stick in NTSF = FAIL
  

Tested in all 4 USB ports. 

  
if you're not getting the 'Press ESC for boot menu' prompt, it means SeaBIOS isn't detecting the USB stick, nothing to do with the way it is formatted. Try another USB stick or SD card, and don't bother/mess with the formatting -- writing the ISO in DD mode renders that irrelevant