My computer stops working,how will i know if my motherboard is dead….

Last night i installed an operating system……. everything is going well until the installation is finished….. and then it went good….. but suddenly the whole pc shuts down, with no beeps, no prompt, no process just….. shutdown…… and when i turn if on “again”….. the red laser near the button just spark once…. and when i look the fan inside its working for just one (1) second, i did try to open my cpu and i’dd check the power supply and its working…. is my motherboard dead for real? or it needs to cool down a bit?