What's wrong with this fern?

[AlmostCutMyHairToday]

Just purchased this Christmas Fern (Polystichum acrostichoides) from an online retailer and it arrived like this - is this normal? Wasn't sure if this is just what some ferns look like in the winter..!
There are some powdery-ish white marks on the back of the leaves (2nd pic). Is there a way of salvaging it? Should I cut off all the leaves? Or is it best to just get a replacement? Could this spread to other plants?
(It's planted outside)

It looks like some kind of mildew.

I'm assuming it's an outdoor one. Ferns do look crap at this time of year, because they have last year's leaves still on. It should be fine, and the new fronds should start to make an appearance soon. Just cut the old ones off as soon as you see the new growth coming.

Thanks @madaffodil . I've had ferns that look a bit worse for wear over winter, but this also looks like some kind of fungal infection. Could it spread to other healthy plants? I'm wondering if it's better to just replace them?

Remove the dead leaves, and it should be fine once it is in the fresh air. If you are concerned, maybe contact the seller?