Nothing, I'm afraid. If you kept the plant covered in fleece all winter, that would partially account for its condition now - they should be unwrapped during milder spells and then re-wrapped if it gets really cold again. Given this winter was very mild, it was likely only necessary to wrap it a couple of times in the last few months. Hopefully, now its uncovered, it should start producing new leaves at the top.

Red cordalynes are usually less hardy than green ones, hence need protection in the winter. But as the winter has been quite mild then perhaps the soil especially if heavy or grown in a pot had become too wet causing the leaves to rot. Bare in mind that they originate from Australia where it is quite arrid. But don't be confused that the lower leaves will go brown and die as a matter of course.