Memorize all starting ticked positions (there's only 4). Then simply tap those (and only those) positions one by one, you'll have everything unticked after you

Memorize all starting ticked positions (there's only 4). Then simply tap those (and only those) positions one by one, you'll have everything unticked after you tap the last one. Caveat: Works if the number of starting ticks is even. Proof: Tapping does not change the state of the tapped checkbox, but flips all others. There are only two states (ticked / unticked) => If a checkbox is flipped an even number of times, its final state is the same as its initial state. And if a checkbox is flipped an odd number of times, it's final state is the opposite of its initial state. There are an even number of starting ticks (n = 4). So by tapping all starting ticked positions, we are flipping the rest an even number of times (n), and the starting ticked positions an odd number of times (n - 1).