1. Find the seam on the ear shell and cut in with the knife blade (be careful not to push too hard).
2. Then pry left and right to pry the unit and the ear shell apart (after pry open the filter and the unit stick together, do not pry open),
3. You can see that the headphone cable is connected to the unit, and the solder joint is clearly visible.
4. The general earphone damage is the wire problem, then just find the broken line or buy a new wire to weld it on.