Hi! I wanted to update my OS to Sierra, it's been 1 hour and my computer screen is still saying it has 20 minutes left. I just bought this computer 3 days ago and I am scared to break it if I touch anything. It is plugged since the beginning of the update. I read somewhere to press Command L to bring up a log that would show if the update is installing thing in the background, but it doesn't show up either. What should I do?