How to check if the LS3 has ever been overloaded to >30kN

No problem, the max. ever seen load is permanently recorded.
Open the Service Menu, and scroll to menu item #13 “Max seen load” to check for an overload.

Note: this only works for firmware v3.220 and higher.
Previous versions do not include this recording feature.

Note 2: this variable can NOT be reset! It is a permanent value!

Note 3: due to a bug in v3.220 the calibration load was recorded here.
In later versions the calibration load will not be recorded, and the LS3 will be delivered with this value set to 0.00.