I got this tip off another ab-er and it worked for me .I dropped my phone in a glass of water. Wrap battery in kitchen roll paper and put in a box with rice and salt and leave in airing cupboard or anywhere warm for a few days. But might not work with laptop but worth a try.
The sugar and rice act as dessicants which draw out the moisture. If its water you may get away with it. Tea, coffee, beer or most other things will leave a residue as mentioned earlier.