I would be surprised if problems with the display ribbon connector caused an upgrade to fail. Maybe I'm wrong, but I'd think that all the software would continue to work and you'd just have a blank display.

I find it interesting that neither this player, nor the one you're trying to drive-upgrade, can be seen by the upgrader software. In other words, you're getting the same symptom from the player you dropped as well as the player you didn't drop.

This, to me, sounds like it's a problem with the PC, with the serial port, or with the serial cable.

It's interesting that hyperterminal works enough to show you the boot logs, but perhaps the receive wire is working but the transmit wire is not? Or something like that.