If you can't fix it, here is an alternative: Remake it from scratch using the assets you have. It will probably take you less time to remake it than to fix it since you already know what events there will be and can plan ahead. Also, as a hint, make it so that the key and door only change the variable if used on the proper map (add in a conditional branch). Basically, any item that should only be used in one map, make sure it only has an effect on that one map. There is another way to do it as well, but it is more complicated so easier to make mistakes.