The firmware we loaded into our device is a HIDmaker USB project, so we can look at it and run it with HIDmaker's AnyHID tool. 

AnyHID shows what happened:

1. A device called "USB Bootloader Pro" electrically disconnected itself from the PC, and
2. A different device called "Demos arrays of values, & Buffered Bytes" connected itself in place of the other device.

Our device is up and running with its new, upgraded firmware!