My laptop is not starting after switching power on.Earlier it used to happen occasionally,laptop fail to start and nothing comes on screen and slowly starts heating up.I used to switch it of and switch it back on after a few hours,it starts working again.But now it doesn't start all despite trying several times across several days.I already tried removing ac adapter,ram reset by removing battery and holding on power,ram remove and reinsert etc. but no luck.Shall i try changing thermal paste,how can i do it myslef.I dont want to give my laptop for repair as there is lot of sensitive data inside. Please help