Diagnosing power supply failure – first step
To diagnose power supply failure, try to find out first whether or not the power is able to come on. You can determine through the fans and drives motors. If you hear beeps or sound of these two devices churning, and there are little lights on the CPU case, then it indicates power is on.
Remove the plug at once if the system case is hot since this can be a ground failure. In the case of PC’s, you can also tell if the power supply is coming with a live screen since monitors are powered independently. However it is a different case with laptops because a live screen may not always be a sign of a working power supply.