I had a bottlebrush last year that looked dead as can be, stems were brittle and brown. Then it started some new growth from the ground in April. I say don't give up! You never know what might come back from the roots.
I just went and checked some of my plants, and am now seeing some new growth started on my orange tree and the bottlebrush (got hit by the freeze two years in a row, amazing it is still kicking).
