My suggestion will be to follow again theGalileo Getting Started - Windows and update your firmware as the Guide states.
Also, could you answer some more questions:
1. Which OS are you using?
2. Are you able to see the ports in Tools>Serial Port? and are you selecting the respective Board?
3. Could you provide us the log that appear after trying to upload the Blink sketch? Does the log says "Transfer complete" at the end?
I got it working. Apparently, the firmware on the board had been corrupted somehow, and I had to re-flash it. Thanks again.