When you clip the board, the conductive layers are also being smooshed together and touch despite the non-conductive layers, which seems to persist during the e

When you clip the board, the conductive layers are also being smooshed together and touch despite the non-conductive layers, which seems to persist during the enlargement of the cut. I imagine the goal of the flat filing is to remove more material from the top layers an “terrace” the layer lines until they don’t touch. As far as the repair is concerned, it seems like the cut only goes through continuous ground or voltage planes. So in a sense, it is lucky no important traces or logic lines are harmed in the process.