Phonak Roger Neckloop Battery Replacement

Just like with Roger Select, I also have Phonak Roger Neckloop in need for battery replacement. Does anyone know battery type? Thanks

Luckily I don’t need to deal with a dead battery (yet). However, I am not sure how you would access the battery. The neckloop case is a continuous case, open only at the top where that antenna attaches. There does not appear to be an obvious unlocking mechanism unless it is the pin hole just below the volume control. Has anybody taken one of these apart?