[znpy]

> After drying it out, a few keys stopped working so I bought a replacement keyboard for ~$20 and swapping it out was rather fast (from memory).

I had an X220 in university (same keyboard part as the T420).

I did wash my keyboard multiple times using dish soap and normal tap water and I only killed a single keyboard (when I didn't wait enough for water to dry out).

You could have most likely just washed the keyboard in warm soapy water, as long as you had enough patience to wait for it to be properly drier (2-3 days at least imho, depending on temperature in your home/area).