[Newsguy]

One of the maintenance items is removing the bumper cover and cleaning your radiators. You'll be amazed at what collects in there: I had a piece of wood about 8 inches long! At that time, you can reposition the cable where you can access easily. I haven't addressed the trunk cable yet on my driver, I must admit. I have another non-running "S" which I have had occasion to remove the rear bumper cover (and engine, several times, transmission, and exhaust< don't ask) and noted the cable was broken. So that is in my future too.
As far as the locking, do you know for certain the immobilizer hasn't gotten wet? It's under the driver's seat and is a common problem if the drains are clogged, or a rain hits with the top down. You might check it to see if there is corrosion on the board.