> when i select USB HDD and hit enter, the screen goes blank for a half second,
> shows no message, and simply shows the boot menu again:
> 
> Boot Menu
> =========
>  ATAPI CD0: MATSHITADVD-RAM UJ8E2
>  ATA HDD0: SAMSUNG HN-M101MBB
>  USB HDD: Generic Flash Disk
>  PCI LAN: Realtek PXE B03 D00

See if these help:

https://forums.lenovo.com/t5/ThinkPad-11e-Windows-13-E-and/Updating-the-BIOS-via-bootable-USB/td-p/1139231

https://www.romanzolotarev.com/openbsd/geteltorito.html

	Andrew