Duo v2 will not boot after firmware upgrade

I tried the USB recovery drive that I created from the link that Deniro posted.  Same exact result, as expected.  The 3 files (uImage-recovery, initrd-recovery.gz, RAIDiator-arm-5.3.13) were all identical to the ones that I had already downloaded and copied to the USB drive.

The Backup button is not stuck.  I can clearly feel it moving when I press it, and I can feel the push back from the button.

I will note that the bootcmd environment variable is set to:

bootcmd=usb start;fatload usb 0:1 0x1200000 /uImage-recovery;fatload usb 0:1 0x2
000000 /initrd-recovery.gz;bootm 1200000 2000000

What would the bootcmd be if a device is booting normally?  I could try entering that command directly to see if the device boots properly.  Then I could work backwards to figuring out why it's always trying to boot from USB.

If someone could send me the environment variables as they would exist for a normal bootup, I can try setting and saving those variables.

The device is definitely not bricked, and it does seem to be able to load a kernel and initrd from either USB or TFTP (I set up a TFTP server on my Linux box to see if that would work...   it does!)

However, when I boot using TFTP, I get dropped into a shell (/bin/ash), because the search for an external flash device fails.  The message is:

Unlocking flash...
Done
Erasing old environment...
Done
Writing environment to /dev/mtd1...
Done
Locking ...
Done
Searching for internal boot flash device...mtdblock4
Searching for external boot flash device...Could not find external boot flash!
ERROR: Could not find external flash device!!
/bin/ash: can't access tty; job control turned off

/ #

(at this point, I'm in a Linux shell with busybox commands available to me)

Compare that to the stage when booting from USB:

Unlocking flash...
Done
Erasing old environment...
Done
Writing environment to /dev/mtd1...
Done
Locking ...
Done
Searching for internal boot flash device...mtdblock4
Searching for external boot flash device...sda

Erasing 128 Kibyte @ 180000 -- 100 % complete.
Writing data to block 0 at offset 0x0
Writing data to block 1 at offset 0x20000
Writing data to block 2 at offset 0x40000
Writing data to block 3 at offset 0x60000
Erasing 128 Kibyte @ 600000 -- 100 % complete.
Writing data to block 0 at offset 0x0
Writing data to block 1 at offset 0x20000
Writing data to block 2 at offset 0x40000
Writing data to block 3 at offset 0x60000
Writing data to block 4 at offset 0x80000
Writing data to block 5 at offset 0xa0000
Writing data to block 6 at offset 0xc0000
Writing data to block 7 at offset 0xe0000
Writing data to block 8 at offset 0x100000
Writing data to block 9 at offset 0x120000
Writing data to block 10 at offset 0x140000
Writing data to block 11 at offset 0x160000
Writing data to block 12 at offset 0x180000
Writing data to block 13 at offset 0x1a0000
Writing data to block 14 at offset 0x1c0000
Writing data to block 15 at offset 0x1e0000
Writing data to block 16 at offset 0x200000
Writing data to block 17 at offset 0x220000
Writing data to block 18 at offset 0x240000
Writing data to block 19 at offset 0x260000
Writing data to block 20 at offset 0x280000
Writing data to block 21 at offset 0x2a0000
Writing data to block 22 at offset 0x2c0000
Writing data to block 23 at offset 0x2e0000
Writing data to block 24 at offset 0x300000
Writing data to block 25 at offset 0x320000
Writing data to block 26 at offset 0x340000
Erasing 128 Kibyte @ 1000000 -- 100 % complete.
Writing data to block 0 at offset 0x0
Writing data to block 1 at offset 0x20000
Writing data to block 2 at offset 0x40000
Writing data to block 3 at offset 0x60000
Writing data to block 4 at offset 0x80000
Writing data to block 5 at offset 0xa0000
Writing data to block 6 at offset 0xc0000
Writing data to block 7 at offset 0xe0000
Writing data to block 8 at offset 0x100000
Writing data to block 9 at offset 0x120000
Writing data to block 10 at offset 0x140000
Writing data to block 11 at offset 0x160000
Writing data to block 12 at offset 0x180000
Writing data to block 13 at offset 0x1a0000
Writing data to block 14 at offset 0x1c0000
Writing data to block 15 at offset 0x1e0000
Writing data to block 16 at offset 0x200000
Writing data to block 17 at offset 0x220000
Writing data to block 18 at offset 0x240000
Writing data to block 19 at offset 0x260000
Writing data to block 20 at offset 0x280000
Writing data to block 21 at offset 0x2a0000
Writing data to block 22 at offset 0x2c0000
Writing data to block 23 at offset 0x2e0000
Writing data to block 24 at offset 0x300000
Writing data to block 25 at offset 0x320000
Writing data to block 26 at offset 0x340000
Writing data to block 27 at offset 0x360000
Writing data to block 28 at offset 0x380000
Writing data to block 29 at offset 0x3a0000
Writing data to block 30 at offset 0x3c0000
Writing data to block 31 at offset 0x3e0000
Writing data to block 32 at offset 0x400000
Writing data to block 33 at offset 0x420000
ls: /sysroot/vpd*: No such file or directory

done
The system is going down NOW!
Sent SIGTERM to all processes
Sent SIGKILL to all processes
Requesting system poweroff
System halted.

The big difference is that "sda" is found as an "external boot flash device" when booting from USB, while nothing is found when booting via TFTP.

Either way, I still have not been able to get the unit to start up normally.