Hi, My Surface RT (almost a year old) has developed a fault where it will not stay powered on for more than a couple of seconds. I recharged it overnight (white light was illuminated on the power adapter), but this morning when pressing the power button, the 'Surface' logo appears briefly (2 secs) before the screen just turns black again. I have tried powering on with/without mains adapter; with/without keyboard attached....still nothing. Has anyone else encountered this (fairly fundamental) problem? Thanks!