Water damaged Samsung Galaxy S3 mini won't sleep?

Hi.

Water damage to phone..thanks to 15mth old and toilet!

Phone was pulled out immediately(of clean water thankfully).I took out battery and dried out what I could and put phone and battery in rice for 24 hrs.I turned on and screen wasnt fully working so put back in rice for a couple of days.

It looked like all was resolved:screen perfect and everything working ok except when phone was idle..instead of sleeping it kept rewaking itself and ends up permanently trying to sleep and immediately rewaking,using up the battery life.

I have tried all the settings relating to the sleep function and have made sure settings aren't set wrong and it seems to be down to the water damage at this point.

Any help would be much appreciated as phone seems perfect otherwise.