Water Damage , led flash working

I left my J5 2016 over the night in a litle water, next day won't open. Didn't knew what to do so i put it in a bowl with rice but for a day only. Next day i checked it but won't start so I put it to charge but didn't charge and while on charge the back LED flash stays open. I send it to a gsm service and they said it has rust inside and can't pe fixed. Can someone give me an advice, if it can be fixed? Cand someone explain me why the back LED flash stays on while charging?