No, you cannot. When arbitrators issue a decision, the decision is final and cannot be appealed. For this reason, many wronged investors will start off by going to mediation in the hopes of obtaining a settlement prior to going to arbitration. If mediation is unsuccessful, the next step is arbitration.
Arbitration is typically less expensive, and decisions are generally issued more quickly than they would be if you tried to file a lawsuit against a crooked broker in the courts, which usually makes arbitration the more attractive option overall for investors who have suffered significant losses.