NEC computer won't boot from USB - I have tried everything I can think of

Question

System hangs after 'Verifying DMI Pool Data.......Update Success"

I have tried:

• Set boot priority (USB boot supported)
• Reset BIOS
• Search for BIOS update - none available
• Booting from CD - this works
• USB flash drive is recognised by BIOS as USB-ZIP
• Re-doing the boot USB with YUMI and Rufus
  • With Rufus tried MBR for BIOS or UEFI, MBR for UEFI and GPT for UEFI

This is an older NEC system; likely not UEFI. Any wisdom is helpful.

Thanks.