Try a prong collar, with harnesses you have no control. The prong should be fitted high on the neck, below the ears and the non-prong area should be positioned at the trachea. Or try a regular flat collar with a muzzle.
Some dogs also go through a fear period and some just prefer being at home. I would drive your dog to a new areas and walk around there.
It sounds like your dog has not had fun experiences walking (choke collar and e collar), I know you are trying to be more positive, but do you let your dog stop and smell, let it enjoy the walk a bit? Are you relaxed or tense?