What causes logic board damage?

It can happen when display gets crushed some power/data lines are pressed together and get shorted, allowing current to go along lines where it shouldn’t. This might damage the connector on the logic board and connected components until the fuse, which is there to prevent the damage goes even further in the heart of the board. An authorized Apple center would usually propose a logic board replacement, but there are around also professionals who can probably fix the board for a fraction of a new logic board cost.