If you are unable to even see the Dell logo screen when you start your laptop, then, there is either a problem with BIOS or the motherboard.
Connect an external screen or TV to any available video output port on your laptop, are you able to get the Dell logo to appear on that screen.
If you are able to see the Dell logo screen, press F12 or Fn + F12 to open the Dell menu and run Dell Diagnostics from there.
If you are still unable to get an image on the screen, you will need to take your laptop to a PC Repair Shop, the BIOS may need to be re-flashed.