samsung i9300 S3 water damage PLEASE HELP
 

Hi , i got my samsung i9300 wet , i cleaned it out so there is no corrosion on the board , however the phone functions fine but when clicking on messages it comes up with an error , and when making calls it only works sometimes mostly its no signal , i have changed the main anttena already ???

any ideas ? do i need to flash it ? if so what files needed ?

Thanks guys ;)