This is the second most tricky step. You need to pull the DC cord out of the stress relief collar (where it is glued in), then enlarge the hole enough so you can cut off the damaged part of the cord and push the remaining part of the cord back through the collar. You'll end up sacrificing just a few inches of the DC cable.

Cut off the DC power cord where it attaches to the printed circuit board. Note carefully that one location is marked +V, while the other is unmarked is ground (Figure 1).

Pull the remaining cord out of the stress relief collar. It appears to be glued in there, so you'll likely end up with a long length of stripped wires. A bunch of black wire insulation remains inside the stress relief collar.

Using a small diameter drill bit, ream out the hole through the middle of the stress relief collar, so it is large enough to pass the DC cord back through it (Figure 2). A bunch of black wire insulation should come out. It may help to progress through several sizes of drill bits, from tiny upto small.

Push the DC power cord through the stress relief collar, starting at the pointy end. Use something stiff, thin and pointy to push it through such as a paper clip. When you are done, pull through about one inch of insulated wire. Tie a knot so the DC power cord can't slip back through the stress relief collar (Figure 3).