If you press the power button on your computer, and it doesn't turn on, it could be that your motherboard is damaged. Your motherboard can incur damage in several ways.
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Dropping your computer's case can warp and crack the motherboard. If the board is bent or scratched during installation, this can also cause it to fail.
A computer case that has insufficient cooling or is in a hot environment can overheat. This can cause the motherboard to warp and some of the parts to melt.
A lightning storm can hit an electrical pole and cause a surge of power to flow through your residence's electrical system. The surge can burn and melt a computer that's not equipped with a surge protector.
A rapid change in temperature can cause the internal components of a computer to permanently warp, rendering them inoperable. This happens a lot with laptops: People leave their laptops in their cars during a heatwave or snowstorm, then they bring their laptops into a climate-controlled environment.
Faulty Power Supply
A damaged or improperly manufactured power supply can send too much electricity to a motherboard, frying its components.