Three buttons on the bottom of the screen not working

Hi I recently received an older version of the Nintendo 3DS XL handheld console with the three buttons on the bottom of the lower screen not working. Has anyone come across this issue? Everything else appears to work except for those three buttons. They don’t feel very positive when pressed either, they don’t feel like they’re doing anything inside the device. Are these buttons replaceable or the switch they go to inside the device?