Hey thanjaisiva, check the apps running in background. Sometimes also the conditions (eg -backcover, temperature) and usage while charging causes this issue. For resolution you can do internal checks in device, hope this will resolve the issue.
please mark it resolved, you're satisfied with answer.
Hey Suhas, devices are only sold by any company after multiple checks in different conditions. If some conditions are changed you can see some problems. Request you to do the normal optimization and if problem exist, need to visit service center.