Why won't it turn on after repair?

My friend got a MacBook Air for free and gave it to me for fixing. Someone had spilled something on it once, and it won’t turn on. When plugged into the charger, the little charge light didn’t light up. After giving it a bath In vinegar then cleaning that off, the charger will light up but still won’t turn on. With a multimeter I checked if there was a charge going to the battery and there was a very small amount going to it. (Not even a full volt I think) So we know the board has power but is there a way to get it to turn on? Or is it too far lost?