QCT1255 BIOS update from pre-boot menu (1.6.4 -> 1.7.1).

Dell Friends,

I'd like to update the BIOS on my QCT1255 from 1.6.4 to 1.7.1 using the pre-boot menu.

I plugged an 8 GB USB flash drive in to a Windows 10 x64 host, formatted it as FAT32 and copied Dell_Pro_QCT1255_QCS1255_QCM1255_1.7.1.exe on to it.

Then I plugged the USB drive in to the QCT1255 using the upper-left rear USB port (the port furthest from the Integrated Ethernet), powered it on, hit F12 and chose "BIOS UPDATE."

I now see a "Flash BIOS" screen which correctly shows the current BIOS level (1.6.4).  Yet it cannot see the new level (1.7.1); the fields under "Flash from file" all show "<None selected>," and "Update BIOS" is grayed out.

How can I make this work?

Thank you very much!

Rob Roy

P.S.  I'd like to use the pre-boot BIOS update method because I'm a FreeBSD user, and I'm trying to avoid the trouble of booting in to Linux or Windows every time I want to update this computer's BIOS.