Is there any way to check and repair the keyboard connector?

I have the same problem. To debug I have bought another keyboard (second hand) and it seems either both are broken or that my connector is broken.

• Neither of my two keyboards are able to light any led (nor caps, nor fn) when I connect them or press them.
• Neither of my two keyboards work after a soft reset.
• Neither of my two keyboards work in the UEFI screen.
• Neither of my two keyboards trigger a device manager hardware change in Windows.

The above tests lead me to think it is a connector related problem...

I have tear down my Surface Pro 4.

The connector appears to be in good condition, no issues on the flex cable connector, no issues in the motherboard pins that connect to it, no issues in the back of the flex cable (there seems to be a ground connection to the case).

Connector pins show either good grounding, 3,26v (~3.3v) or 4.96v (~5v) so it seems all is good in the connector side but I still get no light on the keyboard cover nor any sign of it working in the UEFI menu. Now I only have one cover available for testing...

After a full teardown, that by the way is not fun at all, I cannot find anything hardware related to this not working... :/