A user reports that their desktop computer won't turn on. They mention that pressing the power button does nothing and there are no lights or sounds coming from the machine. As an IT technician, what is the FIRST step you should take to identify the problem?
Reinstall the operating system to rule out software issues.
Replace the computer's power supply unit immediately.
Check if the computer is plugged in and the power outlet is functioning.
Open the computer case and reseat all internal components.