Dell 15R-5521 keyboard problem (KBC?)

[SDNarcia]

Hello, I have a Dell 15R-5521, with the problem that the Ctrl, Alt, Shitf and Num Lock keys do not work, I tested the keyboard with a keyboard tester and it is functional, I also got another new keyboard and the computer has the same problem with the same keys. Check continuity between the ZIF connector from the keyboard to the KBC and all pins are correct. I cleaned the ZIF connector and the KBC and I still have the same problem. I reinstalled windows just in case, and it didn't work. I updated the BIOS to the latest version A16 and there were no changes.

As additional information, I deactivated the egpu because it was already having problems, could it have something to do with it?

I have the following keyboard connector measurements:
Pin 1 - 2.1v
Pin 2 - NC
Pin 3 - NC
Pin 4 - 5v
Pins 5 to 21 - KSO correct continuity to KBC
Pins 22 to 29 - KSI correct continuity to KBC and there is 3.3v in all
Pin 30 - NC

Motherboard VAW01 - LA9101P Rev: 1.0
EMain BIOS Winbond 25Q32FVSIQ
EC BIOS Winbond 25Q16CVSIG
KBC ENE KB9012QF A3

Could it be an EC BIOS problem? Could it be solved by reprogramming it? Or is it directly a KBC problem? I attach the diagrams. I appreciate any help.

[mcplslg123]

If there is no corossion,continuity between kbd connector and KBC is fine,then very very likely kbc chip itself is bad(as kbd is ruled out by you). KBC firmware at fault is very unlikely.