I am sorry you are having problems with your system but let me help you.
I would like you to do some steps to diagnose or at least try to discard some possibilities of what the problem can be.
Please try this and let me know:
- Have you tried a different USB flash drive?
- Have you tried a different USB port? What happens when using USB 3.0 ports?
Besides these steps, can you update the BIOS? Here is it:
I´m booting my D54250WYK from USB.
I´m using the latest BIOS (WY0038.BIO).
On the Devices Tab I had to configure USB Legacy and enabled xHCI Mode with "Smart Auto".
On the Boot Tab / Boot Priority I enabled Legacy Boot and changed the Boot Drive Order by dragging the USB Device to the top.
On the Boot Tab / Boot Configuration you have to verify that USB is enabled under the Boot Devices.
The only thing I was not able to achieve is to auto boot from my USB stick.
Every time I rebbot or switch the NUC on I have to press F2 go into the BIOS and double click on the USB Boot Device entry under the Boot Tab / Boot Priority - Legacy Boot Priority entry.
Maybe somebody has the solution how to auto boot from USB...
Please try updating the BIOS to latest version since it should fix the problem with USB devices not being recognized.
You can get the BIOS at this link: