((a)) ** .—** Each rehearing under this chapter shall take place before a military commission under this chapter composed of members who were not members of the military commission which first heard the case.
((b)) ** .—**
((1)) Upon a rehearing—
((A)) the accused may not be tried for any offense of which the accused was found not guilty by the first military commission; and
((B)) no sentence in excess of or more than the original sentence may be imposed unless—
((i)) the sentence is based upon a finding of guilty of an offense not considered upon the merits in the original proceedings; or
((ii)) the sentence prescribed for the offense is mandatory.
((2)) Upon a rehearing, if the sentence approved after the first military commission was in accordance with a pretrial agreement and the accused at the rehearing changes his plea with respect to the charges or specifications upon which the pretrial agreement was based, or otherwise does not comply with pretrial agreement, the sentence as to those charges or specifications may include any punishment not in excess of that lawfully adjudged at the first military commission.