[Morgeruat]

you haven't done anything wrong, but if u didn't get/keep the arms and legs you need to get them, I don't suggest doing the battle unless you have at least 1 +5 weapon, as you need IIRC +4 min in order to hit him, let alone take him out, there are a number of tactics for defeating Kangaxx try a search, I only just defeated him last night myself for the first time (many reloads later I might add.