this probably is not loading the driver g_serial
try copying the files to the sd boot again
The solution was to go to Intel® Download Center and search for the latest SD Card software, in my case SDCard.1.0.3.zip. After unzipping it I just copied the content to the root of the SD Card. After plugging the SD Card into the Galileo Gen 2 board I booted it up, then I connected the USB to the computer and it worked like a charm. The bootup took a little while, so give it some time. After that the computer plinged and I found my Galileo on COM4.