Your message is a little unclear. If by no charges you mean no criminal charges, that’s one thing, but if you mean no petition in Family Court was filed charging the parents with abuse or neglect, that’s another story.
Children may be removed without a court order and even without a neglect petition. However, a petition must normally be filed in Family Court within three days of removal.
Since your trial apparently occurred months after the removal, the question is whether it was a pre-petition hearing or not. If CPS didn’t file a petition for many months, you might have a case against CPS. But if a petition was filed, then odds are you have no remedies at all.
If a petition was filed and the case was withdrawn mid trial, then there is nothing out of the ordinary by the lack of testimony from the parents.