Share the results for the preboot system assessment.
Connect an external monitor to the system and then press only the power button to see if there is any display on the external monitor.
Update the system BIOS from the link http://dell.to/1bDPDqb and then check if the system boots normally.
You may refer to the link http://dell.to/176grvH for steps on how to update the BIOS.
Keep me posted with the results. I will be glad to assist you further.