I’ve got a 2560, and when I plug it into my Mac (running OS X 10.6.4), nothing appears in /dev/tty* to indicate that the board is recognized. Consequently, I can’t upload sketches to it. On my Windows machine, attaching it results in an “Unknown Device” notification, and I can’t successfully install the .inf.
Is there something I can do to fix it? If not, can I return it for a replacement?
The board is powered when plugged in, and the factory-installed sketch runs fine (LED blinks), so maybe it’s just the Atmega8U2 chip…