Just a thought... Is there damage right where a chock would rest behind the nose wheel? Tough to tell for certain the the pics, but the chock lines up with the break it seems.
Starting the engine with the chock aft of the wheel can cause the nose to squat down with the fairing getting damaged, possibly causing a weak spot that gave out during the landing roll.
Probably not the cause, but if there's any aligned indentation on the underside and this history it could be contributory. My 2 cents, and may be worth less!
