It's due to any liquid or water entered into charging port. Just dry it or place under rice for few hours so it would dry up. Make sure screen is been protected.
We apologize for the inconvenience caused. Regarding your concern we would suggest you to visit nearby Samsung Service Center in order to get your device physically inspected by the Service Engineer. Please find service center details in the link provided -http://www.samsung.com/in/support/servicelocation. Be sure to hit ♡ when you find an answer that works for you. For Further assistance, you can get in touch with us via Live Chat option by following- http://livechat.support.samsung.com/Customer_new/IN. You can also connect us via Samsung Members web community by following mentioned url-https://community.samsungmembers.com/en_IN#/
