Did you dip the coral? I had a similar event happen when I left the corals in CoralRx for 15 minutes. If no dip, I would think a containment. Lotion or soap on hands, soap on the container you used? I know my dishwasher leaves residue now and then. Try again with a hardy birdsnest. Someone in your club should give you a frag. Sorry fellow reefer!
This post reminded me of something not yet mentioned - When you move corals around - especially zoos - they can release toxins. Though it looks like you have a pretty big tank (can't really tell) - it could be that something released toxins in the water - especially with the longer drip method. For example - In my tank - no matter what I do I can not grow 'birds nest' (except 1 of them) - within 1 week they are dead - this is despite several other corals that have thrived for months/years together. Do you run carbon?
Another thought you had the frags in 'small bags' with little water - Could the temp have changed significantly even during the 20 minutes that you drove home? Then when you quickly added them to the tank for 10 minutes - the temp rapidly changed again?
I agree with others low light will not kill coral in 2 days. 1. Corals are routinely shipped for 12-24 hours in complete darkness. 2. During severe storms which can last for days on the reef the lighting can become extremely low - and corals don't die.
Whenever I get new coral (now) - I ask the LFS - what is your SG, alk, what par etc the corals are at and I match those as close as possible in the tank (if I cant match them - I don't buy the coral). Just have had too many experiences just like yours.
. Good luck

