Many electronic toys and devices have button batteries. They are very dangerous for young children if swallowed or put in nostrils or ears. Go straight to your nearest hospital if you think this has happened.
If you think your child has been poisoned, call the New Zealand National Poisons Centre immediately on 0800 POISON (0800 764 766). Do not try to make your child vomit or give food or liquid until you have been given advice.