WASHINGTON, D.C. — The $930 million “patent trial of the century” between Apple Inc. and Samsung Electronics Co. could be heading back to U.S. District Judge Lucy Koh’s courtroom for a little more tweaking.

A Federal Circuit panel posed searching questions for both sides Thursday, with a partial remand emerging as a possible outcome, as the trial that mesmerized Silicon Valley in 2012 went up on appeal in a mostly empty Washington courtroom.