Imagine building something that the only safety margin and back up is -'4 days of oxygen and a couple of spare blue tooth controllers' . These idiots seemed not to have even bothered with an underwater locator beacon - or any type of emergency retractable sonar boom to send and receive low frequency morse communications or it seems zero remote miniature submersible to search from the ship with. Other than Un-survivable catastrophic implosion - if they are not rescued alive, wonder if there is some final moments recorded on cell phone video or a cabin footage cam. As crass as it sounds, the idea that there was an operating malfunction caused by a flat blue tooth controller - and then no one thought to ensure the 2 spares were checked and fully charged before the dive would just be typical clown world.