In my country many use a mesh floor open during winter, and they bees are alive in spring.
But it makes not worse the solid bottom.
a mesh bottom come into use with Danish polyhives 20 years ago. As far as I know, no one used
such before that. Others say it varroa bottom.
If you have a mesh floor, don't keep then upper ventilation.
If you have solid bottom, keep then finger size upper opening.
If you want to save winter food and to get faster spring build up, keep instulated brood boxes.
Some condensation makes no harm to bees.
a dead hive doe not make you a bad beekeeper. What ever domestic animal you keep, sometimes some animal will die and it was not your fault. It just happens.