Mega 2560 connected to Vista.
Basic Blink sketch uploaded with 250 millisecond watchdog code added.
Pin 13 LED now flashes rapidly.
Sketches will not upload.
Releasing reset while trying to upload doesn't work. LED flashes fast as soon as reset button is released.
AVRdude responds with timeouts.
It will go into DFU mode and USB driver installs but Flip or AVRDude cannot open/find USB device.
Disable "AUTO RESET" did nothing.
What do I need to do to get this Mega working again?