http://www.courts.ca.gov/998.htm
A panel of three judges will hear the appeal. Juries determine questions of fact. The facts in the case are not disputed on appeal. Instead, the party appealing will argue that the trial court erred in some way, often procedural. It is possible to get the entire case sent back to the lower court to go through it all again. Or the lower court's award could just get reduced on appeal, which is probably more likely.