My iPhone 4 just started going dead out of nowhere. Sometimes when I connect to iTunes it will come back but I have no idea why it goes dead in the first place. Yes, my battery is fully charged. Also it won't let me complete any updates. Last update was about 3 weeks ago when imessage was enabled. Getting annoyed. Apple store sent me away telling me to update it. Going back today to demand a new phone but had anyone else experienced this?