My bro is using this phone. The screen sometimes go blank(black) for a while, and have to slide the slide thing a couple of times before it show back whatever its supposed to be showing. And sometimes the screen overlaps, or lari, like showing half of the words, or the words at the bottom showing up at the top of the screen, like the screen lari a bit, but then it return back to normal. Sometimes the screen even showed upside down. Is that normal? Happened yesterday, v4.2... update to 4.81, not that much better. Any suggestions?