It's gone. Throw it away. Don't waste your time trying to save something that has close to zero chance of surviving. It is not hard to find another one of these.

Almost no orchids that normally keep their leaves for multiple years should have a complete winter dry spell. This one is included. Cool temperatures, not drying out, triggers flowering. In habitat there is occasional dew in winter, and plants get some water. Some people say you can induce flowering by drying out the plant, rather than exposing it to cool temperatures, but I think this more often kills the plant.

Dendrobium kingianum isn't a great plant for people with extremely cold winters. It's hard to give it enough light to flower the next spring without using supplemental electric lighting. It's hard to give it low enough temperatures indoors to flower, unless you shut off the heat to the room where you keep it. And it's very susceptible to spider mites during a typical indoor winter.

Maybe I’ll move mine somewhere brighter this winter and see if that works.