An Appellate Court is not (usually) the Court of original jurisdiction. So, in many cases you would start at a Federal Trial Court (District Court) and would have a normal trial. If you lost, you could appeal to the Appellate Court, who would review the record (only) from the Trial Court for clear error, bias, etc. A new trial does not occur at the Appellate Level, unless it is a court of original jurisdiction.
Explanation: When we say an official has been impeached, that means the official has been accused of crimes or serious misconduct and must stand trial.
