Fwiw, my rainbow echinata likes the light. I would gradually move it into some light...not right up to the top of the rocks in one day but a couple inches, give it a day and see if it starts to react. Abrupt frequent changes in light and flow will kill it for sure.
What did you try to feed it with? Mine doesn't do well with larger food but always responds to smaller particles. If you're using frozen fish food try chopping it up really fine, turn off the pumps and very gently squirt it toward the coral with a turkey baster or similar. If your fish or inverts steal the food cut the end of a 2 liter coke bottle off and cover the coral for protection.