Having a manual ticking checklist allows the student and/or teacher to take control over their own progress through a checklist.
Turn editing on
Click on the edit icon () next to the checklist activity.
In the checklist activity, go to Edit settings > Check-off when modules complete > Yes, can override.
When you are finished, press Save and return to course
When in the student view. The tick boxes that were hollowed out in the previous chapter are now clearly outlined, meaning that the mark for the checklist can be overridden.