Hi delacroix,
Please try running the Dell Diagnostics again to check the hardware functionality. Power off the computer -> restart the computer, press 'F12' key on the Dell logo -> Select ‘Diagnostics’ from the boot menu.
Incase you are unable to run the Diagnostics using the above steps, use the following method and see if you are able initiate it. Press and hold FN key, simultaneously press the Power button. If the Diagnostics is initiated, let it complete.
Please share the findings.