The electronics module 100 comprises a controller 103. The controller 103 is arranged to operate in a first power mode and a second power mode. The first power mode consumes less power than the second power mode. The controller 103 is arranged to transition from the first power mode to the second power mode in response to an input unit of the electronics module 100 detecting an input event. In the second power mode, the controller 103 is arranged to receive a signal from a sensing unit of the wearable article, determine from the signal whether the wearable article is being worn. In response to determining that the wearable article is not being worn, the controller 103 is arranged to transition from the second power mode to the first power mode.