Computer made a short out smell then died and won't turn on

While I was writing an essay my computer screen suddenly froze and it stayed that way for about a minute while not responding to any commands... I refused to shut it off because I would lose a good portion of my essay but after another 30 seconds I smelt a electrical short out kinda smell and right after it died. Now it won't turn on I opened it up to cool down incase it over heated and nothing... Then I unplugged it and plugged it back in and tried and the lighting in the case and the fans turned on for about a second before it died again. It only does this if i unplug from wall then plug it back in and try...I figure it cant be a power supply issue cause the power does come on for a second but I can't figure it out because if it's not the power supply then wouldn't the power supply fan stay on? So do you think it is CPU, hdd, ram, mobo or the power supply? Any help is appreciated as I don't want to go o tiger direct and pay 50 bucks for diagnostics

thanks in advance