Reboot lead to Loading Circle

Hi All,

I just recently purchased a new mac book pro retina late-2013 and I am planning on upgrading the SSD in it. I was told by apple support that I should install OSX to an external flash storage device so when I plug in my new SSD I have the security of reinstalling OSX from the drive, even though the SSD should install OSX from online. I was in the process of installing OSX to the drive from my MacBook but I fell asleep, considering it was going to take 8 & 1/2 hours I think thats understandable. I woke up and I saw that the screen was just showing a blank screen with the grey apple emblem and the grey loading circle, the one that has lines pointing outwards from the middle of the circle - going around in a circle - fading from dark grey to light grey. It's has been sitting on this screen for hours now and I am not sure what to do, because I don't know if the information is actually done being loaded to the flash drive, or if it has some weird 10 hr finalization period after the download, or if it just took a crap and decided that in the middle of the download it wanted to show the bank screen and the loading circle with the apple emblem. Thanks for an help,