My first console was an NES that my mom had before I was born, and I remember being told by my older sister that you can clean NES cartridges with q-tips and rubbing alcohol to make them work if they don't turn on. When I was 4 or 5 years old, I remember that I was trying to play Zelda 2, and no matter how many times I cleaned it with q-tips and alcohol it just wouldn't work, so I figured the NES must need cleaning too. Since an NES is much bigger than an NES cart, I took the bottle of rubbing alcohol...
...and poured it inside the NES. It never turned on again.