Some keys of my mbp2015 keyboard suddenly stopped working(no accident)

Problem

The keys zxcvbn, in my mbp 2015 suddenly stopped working from one day to another all together. This is almost the whole bottom row of keys. Left shift is still working and , also is working (English keyboard).

Info and context

I guess that some cable is broken and thats why the whole line of keys stopped working all together. I've saw a couple of tutorials to change the keyboard, but I have to dissemble the whole computer, which looks kind of overwhelming. I have some experience with hardware, like changing the battery of the mac, and fixing some other easy things. So last resource I can do this.

The computer is kind of old, but I was planning to give it to my father that currently can't afford buying a new one. And it has 16Gb ram so for browsing and normal stuff still works like a charm.

Main question

Are there are any other failure points easier to check before dicing into this HUGE mission? Like changing some flex cable?

Already tried

I already tried reconnecting the cable that goes to the trackpad and keyboard over the battery, to see it that was doing false contact, and I am having the same problem. Also I did all those canonical things like turning on and off, reseting smc, etc.

Thanks!