That wouldn't explain his display being blank or him getting no response from the serial port, so it looks like he may have more than one problem with this player.

Through IM last night, I had him try to install Hijack on the player. As a control, he installed Hijack on his "good" player using the same computer, serial cable and power supply. It worked fine on the "good player". When we tried the "bad" player, it failed. "Error status in readbyte 16"

Having the flash erased would explain the behavior of his player, but I can't figure out why we can't get Hijack on there.