Turn off the system. Unplug the power cable and all external Peripherals. Press and hold power button for 15 seconds. Plugin the power cable and turn on the system. If the system again gets stuck on Dell logo, press F12 and check if you are able to open One Time Boot Menu.
If yes, select Diagnostics or Utility Partition and perform diagnostics.
Please keep us posted with the results.
Thanks & Regards