As long as there is green I'd say there is hope.

What happened to it??

Does not look good though, in my opinion.

The problem is cold damage.

That soil looks very heavy, possibly poorly drained. Cold, soggy poorly drained soil would be the worst conditions you could keep it in. I'd be inclined to repot in good soil and check the roots and base of the plant in the process. Sometimes fronds will retain a bit of green even when the base of the plant is rotted out.

I repotted it in the same pot but filled it in with a more well-drained soil but left some of the original soil on top.
All the soil in the pot was very wet but the main roots seemed to still be ok.
Any more advice would be appreciated.