Computer not booting up

Hi, I own a Dell Latitude 7480 recently when i tried to power on the laptop an error message appeared the stated that the fan had failed to start when the laptop booted up. It had a few option for me to choose one of which was to press F1 and retry the boot which I did. After that the computer is more or less unresponsive, the power light is on, I cannot turn it off no matter how long I hold down the button, the only way to turn it off is by disconnecting the AC charger however then the power light wont turn back on and once the charger is plugged back in it the power light automatically turns on. The screen never turns on at any point, as far as I can tell not even the backlight is on.