From this I assume the cargo fire extinguisher was fired and the fire light went out. All the comments about evacuation or disembarkation seem to assume there is still a fire. Why do they assume this?
I can not answer this question, but I'd be rather nervous & surprised if they designed a system where the fire extinguisher was fired, the fire went out but the fire warning didn't indicate this.
The cargo compartment fire warning, warns you of SMOKE - not a fire. So even if the fire causing the smoke can be suppressed with halon, the smoke would likely still be present.