Dwarves and Doguns part 2

So yesterday, I started this quest right, and I got to the stage where I used a cannon to blast through the wall. I entered it and it tp'd me to the slums. At this point i use a scroll to go to forge because my lil bro wanted to do it with me (he's lvl 70 and I'm 105) now when I come back to the quest the wall is fixed and I cant use the cannon.

What to do???
P.s. I believe I need this quest in order to do 'A hunter's calling'.

 

can you come to the slums from rodoroc? there is an entrance in rodoroc

 

^ as said above, there's another entrance in Rodoroc, should be at (1089, 21, -5034), if you've already done the stage of getting into the slums once I think it'll let you in
if not, try retracing your steps from the armory bit and hopefully it'd let you use the cannon then

 

thanks man