have I killed a "new" 820-2347-A board?

I have (originally) an MB562 iPod 120GB, with 2.0.1 firmware.

I converted it to 256GB iFlash SSD and 820-2347-A logic board with 2.0.4 firmware and new battery.

When I first connected it to iTunes, it appeared to restore immediately and normally.

Then I began to sync it, with a starting playlist of 2400 tracks. Obviously that took a while, so I walked away. When I looked later, there was an error that one track had failed to sync. I accepted the message and it appeared to continue, showing "Finishing Sync. Then iTunes appeared to lock up and would not respond to key commands.

I used Task Mgr to close iTunes and was going about ejecting the iPod. I may have disconnected it before it displayed OK to Disconnect.

Since then, as soon as I turn it on it immediately goes from Apple icon to the red X screen. I cannot get it into Disk Mode, and the computer (WIN10) does not see it. It will display the diagnostics menu.

Have I "killed" the board is there still some way to get iTunes to see it again?