So after 4 sticks of Dynamite, 6 dynamite arrows the door was still on. I threw 2 fire bottles at it and the door fell off. Not sure what to make of that but if any one else runs into this, hope this helps.
After I kill all the guards and drivers, no matter what I do, place dynamite and light it, place then shoot it, throw at it, from either side the doors are not coming off. What am I doing wrong to blow the doors off?