Let me provide you some troubleshooting steps so you can diagnose your problem yourself instead of visiting to the service center. Step (1):Perform Battery Optimisation.
Settings > Select Device Maintenance/Device Care > Optimize > Optimize all options like Battery, Storage and Memory. Step(2):Turn off Bluetooth, Wi-Fi, mobile hotspot, NFC, etc
a). Swipe down on the home screen to open the notification panel.
b). Tap on Bluetooth, Location/GPS, Wi-Fi, Mobile hotspot, NFC, etc. to turn off. Step (3):Kindly check whether the mobile network fluctuates frequently or network signal is low in your area. In both cases, the battery will drain considerably fast. Step(4):Reduce display brightness level.
a). Swipe down on the home screen to open the notification panel.
b). Turn on the Auto-brightness option if available. Step(5):Adjust screen timeout settings.
Go to Settings > Display > Screen timeout > minimum screen timeout. Step(6):Update apps.
Kindly check which application is or interface is using more battery from device care. And try to update the app or avoid using that app. Step (7):Close background running apps.
Tap on recent key and close the background running application. Step(8):Turn off auto-sync of e-mails, app data, etc.
a). Swipe down on the home screen to open the notification panel.
b). Turn off the auto-sync option. Step(9):Check device in safe mode:
Power off the device > Press and hold the Power key for one or two seconds to turn on the device > When the Samsung logo appears, press and hold the Volume down key.
Exit safe mode: Restart the device. Step(10): Try your device in safe mode. As you were facing battery drainage issue in your device, I have provided you some basic trouble shooting steps and your concern has been resolved. "If the problem is solved click the three dots & click solution".
