The yellow bang "!" on the COM port in device manager suggests that there is no valid driver installed for the serial port which connects your Galileo.
This happens on my Windows Laptop too, yet on my Apple Mac it just works without any driver.
On windows it evaluates as "Gadget Serial v2.4" so we need to download and install this driver.
On my system, I downloaded the Arduino Zip from here and extracted it to a folder.
Then, double click on the port in device manager, and select 'update driver' then "Browse my computer..." so that we can specify where to look for the driver. Then browse to the folder you unzipped the Arduino zip into and make sure 'include subfolders' is ticked. It then found and installed the correct driver and the serial port worked and Galileo was detected.