Unfortunately button may not be visible in ray directly!
May be she swalowed it rather than putting into nose!
If it had gone to bronchi it may show indirect evidence with what is called atelectasis
in lungs or obstructive emphsema. (medical terms for showing foreign body in breathing tube)
Absence of symptoms is a Good sign. Though this has happened before and diagnosed and removed after few months by bronchoscopy!(rarely in a few cases)
God bless and all the best