Gigabyte B560M DS3H: Keyboard not working

[Habakuk]

I just built a new PC for my youngest. Here's what I put together:

CPU: Intel Core i3-10105F
MOBO: Gigabyte B560M DS3H V2
GPU: Nvidia Geforce GTX 1650 (4GB)
RAM: 16GB Crucial Ballistix 3200Mhz
SSD: 256GB Patriot P300 (NVMe SSD)
POWER: 400W be quiet! System Power 9

I assembled everything and gave it a first shot. However, we never got past the point shown in the attached file.

Somehow the keyboard seems to be not working. I tried various keys, F11, DEL, etc. No reaction.

 

I tried different USB ports (front, back, 3.0, 2.0, designated Mouse/Keyboard USB at the back). No reaction.

I tried three different keyboards, 2 USB and I even bought a PS2 one for this purpose only. No reaction.

Both USB keyboards are working fine elsewhere, but here ...

 

No OS installed so far as we couldn't get things to work. 

Any idea where to look and what could be the issue?

[LTTFan16538228]

Can you inspect the whole motherboard for any visible damage, and was it refurbished?

[Habakuk]

No visible Damage.

I bought it brand new.

But yes, this was the only thing left in my mind... a defect motherboard.

[Habakuk]

Update:

I disconnected everything, just kept the GPU, 4 GB RAM and the SSD.

 

All other connectors (HW LED, Front Audio, second 4 GB RAM) removed.

PS2 keyboard works now. I am trying to install Windows 11 before re-assembling everything, but Winows doesn't recognize the Patriot P300 SSD.

 

Looked for a driver or something, but coudln't find one on Patriot website.

Anyhow, I'll see now.

Once everything is back working, I'll post it here.