Galaxy S3 Water damage

One day it rained heavy, and i forgot i had my s3 in my pocket and when i put it out, it wall all wet, it seemed to work fine for a moment, but a day after there was no sound coming from it and battery charginh was very slow. I put it in rice for a week but with no sucess.

So the phone works fine but:

- charges very slow
- sound does not work
- random turning off

is there anything to do other than replacing the motherboard?

Thank you in advance for your help.