Sounds kinda of unusual but likely related to poor contact of the batteries contacts, as some weird behaviour has occurred for some folk.
How long have you had this Pandora and has it always done this?
Otherwise as a quick test I would suggest removing the battery entirely for a few minutes and then re-inserting it. This can clear some issues and for me fixed a seemingly bust right nub. Some folk used some paper inside the battery cover aswell, to ensure a tighter fit against the contacts.
Others will no doubt have further 'proper' tests you can try.
Happy xmas and I hope you get it sorted out.