Hopefully, the battery service was performed by an Apple authorized shop. You can confirm by looking for the name of the shop that you used using the link just below:
Find Locations
Perform a Forced Restart on the phone. Follow the instructions very carefully, as this is a bit tricky. You may need to repeat this several times.
Force restart iPhone - Apple Support
There are only 2 possible results when you perform a Forced Restart:
1) The phone returns to normal operation.....or.....
2) There is a hardware problem with the phone that will need attention at the Apple Store (make an appointment) or take the phone to an authorized Apple Service shop.
You can find a list of authorized service shops in your area using the link above.