To get started & ensure the chamber is the root of the issue we always recommend testing the additional chamber provided in your Plus kit. If the battery is functioning as intended and your chamber won't heat you may be experiencing a connection issue.
In this case we always recommend cleaning the gold connection pins located on the top of the battery and the underside of the chamber. This can be done with a cotton swab dipped in ISO and will help alleviate any connection issues occurring between the atomizer and battery. Sometimes even the smallest bit of debris can prevent the pen from functioning at its full potential.