My data is wiped out after a battery service
Sounds like they just replaced the device and gave you a new/refurbished one. Your original device will be fixed (if possible), and then it will be wiped and turned into a refurbished unit.

If you didn't back up any of your data, it is gone. Hopefully you did; I'm pretty sure anytime you send in a device for service, they warn you that it could be completely wiped.