I hate to be the bearer of bad news, but that foot is probably toast. Once it starts to smell, the tissue is very likely dead.
Cutting off circulation for even an hour or two would likely have killed the foot, but two days sealed its fate.
Can you post a more focused picture of the necrotic foot? I'd like to see if the foot is beginning to auto-amputate. This would be the normal sequence after a severe injury to the extremity. The chicken's body walls off the infected tissue, rerouting the blood supply away from it to avoid carrying bacteria into the bloodstream. If this isn't occurring, your hen is in serious danger from systemic infection, and an oral antibiotic might be a wise choice.
By the way, although it likely didn't affect the foot one way or the other since irreperable damage had already been done, hydrogen peroxide can be used to clean a wound, but after that one application, continued use destroys new cell growth and should be avoided.