Seems there's multiple bugs on this quest, unless I'm not understanding what's supposed to be done on this quest.

If you convince the guard to let you speak to the boss, he calls out "you should listen to these folks", but all doors remain locked. If you take the key from the guard, it doesn't fit any of the doors. If you pick the locks, and take everything, including the weapons, you still can't turn in the quest.

If you fail the quest or can't complete it, there's no dialogue option for ending the quest.

I've tried this with 2 different characters on 2 different resets, and got the same results.

I still haven't come across this quest. I keep seeing bug reports, but oh well!

As of v1017, door keytags fixed.

Are you trying to give up the quest at the quest giver? He uses the same dialog nodes and scripts as every other NPC. Same for trying to turn in the quest item.

Note: Just because some of the loot is weapons doesn't mean those are turned in as a quest reward.

Are you trying to give up the quest at the quest giver? He uses the same dialog nodes and scripts as every other NPC. Same for trying to turn in the quest item.

After failing to complete the quest, I return to the quest giver, who greets me with something along the lines of "Ah, you've returned." But the only dialogue option is "End Dialogue".

Found the issue. Turns out he had two different "Ah, you're back" nodes. Fixed in v1017.