Push on alternating sides of the battery connector to "walk" it out of its socket.

If that doesn't work, use a pair of tweezers to firmly grip the sides of the connector and pull straight away from the socket. Hold the tweezers closer to the connector to get a better grip.

Additionally, if the previous step didn’t work, use the arms of a pair of sharp tweezers to gently push the connector out of its socket by inserting them into the cutouts.