The state of the checkbox (checked/unchecked) is usually somehow reflected in the attributes. You can attach a log message to the 'Attributes' property of the find web element to see the state of the checkbox.
Another way to do it is to select a checkbox in developers’ console (in Chrome Ctrl+Shift+J) and see if the attributes change with the state of the box, i.e.
If they do, here is how you can use that to create script in your case:
For more details please refer to this video.
For any clarification, please contact our Priority Support.