Hello IlliniBird,
Thank you for using Apple Support Communities!
Based on what you mentioned, it is important to have the details about your service in this concern. If you took it to an Apple Authorized Service Provider, they likely act as a liaison. Or, it is it possible that they would have been more involved considering they just serviced it. Your issue can happen if the iPad was not correctly serviced (even for a battery replacement), but you may be able to get help where you are when you Contact Apple for support and service.
Also, take a look at this document: If Touch ID isn't working on your iPhone or iPad.
Best wishes!