A friend of mine got his 4S screen replaced due to a crack, and after two screens it worked again. However, for a day or two there were faint stripes and blogs flashing on the screen when displaying darker colours like the notification centre. Then it just powered off completely and now nothing shows on the screen and none of the buttons register. It doesn't appear to turn on e.g. There's no vibration when using the mute switch, no Siri when holding down the home button. After being plugged in for 5 or so minutes the charging sound will occur at regular intervals (about every 6/7 seconds) but still nothing on the screen (some sort of boot loop?). Any suggestions as to what could've gone wrong or is the phone a brick now?