Updating a rooted Galaxy S3

When I got my phone, I rooted it the day I got it, of course. Yesterday, I got a notification that there was an update available for Android. I downloaded it and tried to install it, and it seemed to have worked until it restarted to actually install the software. It just opened the screen that looks like a terminal (the one you use when rooting the phone), and showed the Android bot guy with a red exclaimation mark over him. I almost panicked, but fortunately restarting reverted it back to normal. The update failed though, so how can I actually update it? Furthermore, what is this update all about?

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Nothing?

I also do not know how it would be.