Hi. My Dell laptop e7440 screen went black. But power, capslock and battery light goes on everytime I switch it on. I have tried several combination keys to troubleshoot such as Windows+B, Shift+F8, F11 and F8 however there's still no any signs of life in the screen.

Im trying now to connect it in the TV through HDMI cable, but there is no display. I pressed Windows + P, still no display. This is my firstime to connect it on externals. I wonder if it still needs to be unlocked by users. (meaning I still need to unlock my laptop before windows + p works) or is there any more command keys to press so it will directly display. 

Thank you in advance. It will be such a great help.