" Only way is to remove the chip, and solder in a new one, which few people can do, especially these days "
and that's what was done to our TQS back in early 2000. Ours was done by the late Geoff Everret at Automotive Developments at Oddington. He disappeared into his house ( next door) for about 15 mins and brought it back with new chip in a new carrier! ( think that's what he said.)