You should talk to a housing lawyer or nonprofit agency rep, but this sounds like an escrow-triggering event. If the place is not habitable, it is not habitable.

It also sounds like you should not finish unpacking. Get hold of that agent, tell him this is likely not going to work, and ask what he can do for you. Seriously. This landlord is shit. You are only going to get extra shit from him after you cost him money by making him fix the windows. I know you like the place, but it's not sounding good.

The gut job just does not attract me as a tenant. (Also, if they replaced walls, you seriously want to know about where the wallboard was from these days.) I'm a worst-case-scenario thinker and so my mind is going straight to "meth fumes or mold from a grow house," but that's me, catastrophizing, and also it's more common in the burbs than where you are. But those are things to keep in mind: a gut remodel is not something you do for no reason.