Apple newbie here. I tried to update OSX from Mavericks to Yosemite. The downloading failed. It showed me a message saying "an error occurred". So what I did is to search on google what were the recommendation. I followed this video tutorial to reset the download again here.
After doing that the message was gone although the button now turns to just "Download".
It prompt me to restart my computer to install. But I was worried because I know that the download failed. Any suggestion on what to do? Is there any way to re-download the update just to make sure I have all the files.