If the firmware update is taking an unusually long amount of time, and isn't completing, there are a few things you can check.

1) Try a different (shorter) cable. USB cables, like all cables, can fail from time to time. I you are using the USB cable provided with the SS, you might try a shorter cable. There is a length limit on USB cables, but in practice, you can see issues arise as you approach this limit. The SS cable is within this limit, but is towards the upper end. 

2) Try a different USB port. 

3) Connect directly to the computer. 

4) Make sure there are no power saving features enabled on your machine that may affect the performance of the USB ports.