Dell XPS 9350 certain keys not working, what could be wrong?

I have a Dell XPS 9350 laptop, and found a keyboard issue as follows:

Certain keys from keyboard not working properly, for example, nothing displayed from those number keys, type "L" key, but shows letter "P" on screen, etc. Boot it into safe mode and got the same symptom. Run the bios diagnostic program, but detect the following error:

Error code: 2000-0415

Validation: 115386

Cables - Check the following cable, jumper, connection, or sensor, keyboard.

I thought this might be the cable connection issue, so I opened it up, and reconnect the keyboard cable with daughter board and motherboard, but problem is still there.

Does anyone have thoughts what could be wrong here?

Many thanks,

Shaun