I am playing squash shortly so can’t check right now but you haven’t read my last post fully. The bottom five vertical lights are used and you count from BOTTOM up so end is light 2, the very top light is not used.
If you have lights 2 and 5 from bottom up lit then that is error code F18 which is a communications error, could just be loose connections between the circuit boards or main power board failure. 🙁