My sony ericsson w580i went through the washing...

Water and electrical devices, whether AC or DC do not mix very well.
The only thing you can do is take all the removable parts off, and dry them using a low heat hair dryer. Some bits and pieces can be changed, but it will end up costing you just as much as buying another phone, near enough anyway.
I would put it down to, a bit of bad history best forgotten and I would buy another phone. It might work OK after a while of leaving it in the sun, but in the end it all depends on how long the phone was in water.