Please share the exact system model. Do you see the Dell logo when you turn on the system? What is the power light status on the system? Do you hear any beeps from your system? I will recommend you to run the diagnostics on your system to check the hardware functionality:
Power off the system completely.
Press and hold 'Fn' key and press the power button at the same time; make sure you keep 'Fn' key pressed when the power button is pressed.
This should initiate the diagnostics.
Keep me posted. Please reply for any further questions.