Trying to flash Davinci XYZ 1.0, nothing but black bars I get nothing but black bars and "Unknown USB Device" from Windows 10.  This is after a failed flash that was otherwise going directly according to plan.

This Davinci has been nothing but frustration for me, and I'm really tired of fruitless Google-Fu.

Much of what I see pretty much says it's bricked;  attempting to jump the jp1 jumper any further does me no good.

Is there anything I can do to actually move forward, or are we in soldering-iron territory now?
I had this occur on my MakerBot Replicator Dual after I tried repairing a blown voltage regulator. If you refer to the previous link to my SE question, pay attention to the comments of Ryan's answer where it is explained that (in my case at least) the main processor was damaged and therefore couldn't properly load the firmware. The machine was able to load just enough to initialize the chip on the LCD screen, but since the main boards processor was blown, couldn't load the firmware to send commands to the screen and continue the boot sequence.

I'm not certain that you're encountering the same EXACT issue, but you have all of the same side effects that I did. Basically, if you're not pro with electronics, your board is bricked. Otherwise, you might be able to salvage the board by replacing the processor, but there's no guarantee that something else isn't wrong or that the new processor was installed correctly.