IPHONE 5 rebooting ALWAYS

Hello, baldanif radhi.

Thank you for visiting Apple Support Communities.

I understand that your iPhone will restart on it's own after Apple or an authorized service center replaced your battery. Here are the troubleshooting steps that I would recommend going through for this issue.

Make sure that your device is up to date and your apps are up to date. If you still need help after updating, contact Apple Support.

If your iOS device restarts or displays the Apple logo unexpectedly

-Jason H.

If you change the battery and the phone reboots, you need to get that battery replaced immediately as it is faulty.