As for now, he has reinstalled drivers, updated BIOS, reboot in safe mode, tried the BIOS hardware test... Everything to no avail. Mass storage devices works well in this port. Input devices do not.

 

But still I'm not totally sure that it is not a software error. 

Easiest and most definitive way to find out is to carefully disconnect all your existing HDD/SSD (to keep safe and isolated).
 
Install a spare (known good) working HDD/SSD. Clean install Windows, basic drivers, and test operation. Takes about an hour or so.

See this thread:  fixed 

Thanks Tesla 1856.

I have not reinstalled windows. but I've booted from an USB recovery drive. When in the screen asking for the keyboard layout to use, I0ve switch the mouse from the working usb port where it's connected now to the failing one. And it failed: no pointer or mouse movement on the screen. So it's really something in BIOS or hardware. BIOS version is 1,0,13 (curioulsy the downloads section in DELL's page shows as the last one 1.0.12). the DELL agent updated it while the remote support session.

The port is the marked one:

befor you take the entire System apart, try Power Drain + Clear CMOS.

disconnect all Cables

open the Side Panel and remove the Coin Cell Battery from the Motherboard.

hold Power On Button for a Minute.

put the Battery back in.

you will need to adjust the BIOS Settings after you are done.

i hope it works.

jlosada wrote:

1. I have not reinstalled windows.

2. I've switch the mouse from the working usb port where it's connected 

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1. Try to find time to do it if you want to know for sure

2. Generally, you can't move your primary mouse to different port after computer boots. Keyboard yes, mouse no.