the faint burning smell means something died. but it's impossible to diagnose what happened in this forum.
do you have a techie friend who builds his/her own pc? they'll be able to help you. otherwise you'll need to send to a shop.
This is the situation; I was trying to be a smart and installing a new hard disk by myself. Sow probably I whose buckle some cables wrong. And than when I started my PC, it whose switch ON, in the second, and than switch of. I sense a light smell of the burning. From then the pc haw no reaction at all. Is my motherboard dead and also a hard disk? And is there any cure or I must to buy a new PC?