Re: what can make a hive smell?
Yes, it could be AFB or EFB, but there would be signs like capped brood w/ punctured caps. But you said there is no capped brood, so i would rule that out w/out first hand hands on knowledge.
Yes, it could be fermented honey. Does the hive smell yeastey? W/ your weather and the granulated honey I imagine that that's what is going on. The granulated honey has soaked up moisture from the high humidity conditions you described.
You said that you requeened this hive soon after. I'm confused? You requeened a dead hive? Or you requeened a weak hive?
Well, either way, did you put frames of brood and bees into the hive that you requeened? This would have helped to make the colony more successful.
"barely any brood (only drones-very patchy)". Meaning only drone brood present and that very patchy? Sounds like a drone laying queen if there is a queen at all.
The answers are the end. The questions are the journey. Journey on.