First of, make the cannon charge pr failed second phase be related to the number of broken regulators. More broken regulators, noticeably less charge. This makes a 4/5 fail distinct from a 0/5 fail, making the phase less of a all or nothing fight.
second, make people load in on a smaller platform above the main platform. This to avoid the “killed by loading screen” issue, and also avoid (to some degree at least) the potential of people just camping and sniping the champ. said small platform may even be made to vanish some seconds into the fight, dropping whoever is still on it into the fight below.