I have a 3 year old Toshiba Satellite C50-A-1DV running ms windows 8.1. When I switched it on the screen was completely black - not even a flicker - no POST or ability to access the BIOS. the pc fan is operating and the HDD is whirring but NO display. I have tried: removing battery and pressing power button, Connecting external monitor via VGA and HDMI, attempted to repair using windows OS repair disk, removed HDD and RAM, Attempted to flash BIOS, run without battery - just mains power lead. Nothing works - HELP Any ideas please.