Get a “No Pull” harness ASAP! They attach to leash at the chest and give you far more control of your dog than a collar. It was recommended to me by a trainer when my basenji was a puppy and after buying one I never use anything else. My dog is 12 now so he’s calmed down, but when he was younger he had the strength of an ox! And only 23 lbs! The naughtiest and least obedient dog imaginable until he was about 3 or 4. Basenjis will kick your butt!
I agree with all the previous comments and would also suggest that perhaps for the first few days to try to block off your hallway so she cannot access it. It’s probably inconvenient for you, but I think it would help her get the message and break her habit while you try to get rid of the odor.
My 10.5 yo basenji also has bowel issues (he was never officially diagnosed with any condition) and he has been on an extremely restricted diet for nearly his whole life. When he was younger one rainy winter he started pooping downstairs bc he hates getting wet. We blocked off the stairs while we thoroughly cleaned the area that was very effective.
Another suggestion I have if your dog loves food is to use her special kibble as treats. It works v well for us. Good luck!