You should be able to call LG customer service and talk to a live person. However, if you can physically exchange the set with the retailer, you will get much faster service. Once you initiate a claim with LG, you may be stuck with the tv and repair visits which could take some time in scheduling. If you can take it back locally, you may be able to get the whole thing resolved much quicker.
Like I said before, I'm not familiar with that particular model or do I know what the US equivalent is. However I have seen a lot of defective main boards in LG sets. From what I read in your post about having to restart the set to make it work, I'm sure that you either have a bad main board or faulty firmware which is basically the same as a bad board. All you can do is recheck your connections and cables and if it still malfunctions, then decide whether to return it or have it serviced.