MacBook Air A1466 unable to detect its trackpad or keyboard

Hello,

We have a Macbook Air that had a little bit of water get onto the trackpad. At first, the machine would not turn on at all. Upon taking it apart, I was able to get it to turn on when I disconnected the ribbon cable from the trackpad to the logic board (I believe it was perhaps shorting out there, and there was a blackish mark on the end of the ribbon cable that goes in the trackpad side). Of course without that, it was unable to find the keyboard and trackpad. I was very hopeful that a new ribbon cable would fix it all.

Since then, I have replaced the ribbon cable, and the computer is able to boot up with the cable in place, but the inability of the computer to detect or use its keyboard or trackpad persists (although it does find the power button).

When we plug in a USB mouse/keyboard (a logitech designed for PC is the only one we have right now) these do work and the computer functions.

I then removed the trackpad and cleaned the place the ribbon cables insert with a soft toothbrush and rubbing alcohol to try to make sure there was no grit or corrosion remaining, but when I put it back together, the problem persists. (Same condition - does boot and run, only can use USB mouse/keyboard)

We have updated the OS because we thought perhaps it was an issue of the trackpad software (firmware?) needing a refresh. This has done nothing but make booting up go slower!

Is there some software solution I should try next? Otherwise I think my next step is ordering a replacement trackpad to install. Does this sound like a trackpad issue, or is there some other place I should be checking for corrosion or scorched up connections? Should I order a new trackpad AND new ribbon cable or do you think the ribbon cable replacement is still OK after being plugged in to possibly messed up trackpad-side connections?

This is my first foray into do-it-yourself Macbook repair and I appreciate your advice! Thanks!