Before talking to the golem, pick up the letter near it, marked by a red dot on the minimap. Speak to the golem and he informs you that he needs considerable repairs; use the 4 pieces of soft clay on the golem to bring him back to coherence. The golem tells you that it was programmed to destroy a powerful demon. To help the golem, you must discover how to open the portal leading to the demon's lair.