I was trying to replace my 2-GB USB with a new stick and I could not get my old QNAP TS469L to boot off the new stick.  The boot process would fall through to the EFI shell.  The EFI shell's "map" didn't show a "fs0" so it wasn't finding any filesystems.

 

Through trial and error I realized my old stick was MBR and the new stick was GPT, and through all the testing of cleaning the disk with diskpart and trying smaller partition sizes and using the unRAID USB Creator tool to restore the ZIP and even a fresh download, nothing ever changed it.  Once I saw this difference I used diskpart's "convert mbr", created the full 16-GB partition, formatted, unzipped the backup and ran "make_bootable.bat" and chose not to permit the efi boot, and it all worked.

 

I really though diskpart's "clean" would reset the disk layout to MBR but that's something I learned today.

 

After it was running on the new USB I shutdown and renamed EFI- to EFI and it booted, which I guess it's only Windows that doesn't like UEFI boot from MBR  so that's something else learned.

 

Just thought I'd pass along the knowledge in case someone else is trying to use ancient hardware with a USB stick that's set to GPT.

 

you may need to turn off secure boot in bios. and setup clover boot menu to use another os. Or edit qnaps linux grub to use and boot form the usb.

https://www.qnap.com/en-us/product/ts-469l/specs/hardware

things all over redit on acomplishing this.
 

 

you may need to manual install the flash drive enabling efi boot flags. There were some reports of the windows bat script being broken and not making a efi flash drive.