A contactless option for checking in books would be to do so by camera. If your device has a camera you can click the Camera Icon next to the Type or Scan ISBN bar. This will turn on your camera and you can center the ISBN barcode within the white square (Shown on the image below).
Under the Put Away column on the far right you have the option to print off the list of books that need to be put back. Simply click the printer icon on the far right.