I have verizon, so it might be a little different than yours, but just go into settings, scroll to the bottom and tap on system updates. From there tap on "check for system updates" and just do what it says. I recommend doing the update over wifi as it will eat up your data plan.
I've tried looking online for an answer, a few people seem to have had that problem as well, but I could find no fix. I would try going to your carrier, or calling a help desk (even though they help about 50% of the time) but they may not have released it for your version (metro) Good luck, sorry I couldn't be more help to you