My advice would be to return the remaining damsels - even if you don't get store credit. I mean they are what 3 bucks each? I would lose 5 - 10 dollars to save two fish, JMO. Then allow your tank to cycle naturally. Since you already have ammonia and nitrite your cycle has already started, so the shrimp isn't needed. Make sure you have some base / live rock and sand for the bacteria to populate, then wait until you have 0 Ammonia, 0 NItrite, and >0 nitrates, then you can reintroduce some fish (small ones at first).