Why would there not be double, triple, even quadruple redundancy for a locator beacon? And if there was, how could each system have failed? Hoping for a speedy resolution for these people, and the best possible outcome.
What's the point of a locator beacon when anything going wrong begins with the implosion of the vessel and the death of everyone aboard? How would such a locator beacon work under 4000m of water?
Its not necessarily an implosion that can kick off a cascade of failures, a thruster could have gotten stuck and sent them into a spin. It looks like the submersible was heavily dependent on software if you take a look at a few the videos explaining its construction.
All those switches covering the walls of the Alvin sub (or any other real scientific submersible for that matter) are there to control every aspect of the sub at a hardware level. It doesn't look like the Titan had that level of control, at least not accessible quickly in an emergency.
The thing is, if something went very wrong like that, the default would be to cut the ballast (which in this case is held on by electromagnets) and surface naturally. Same with power loss or pretty much anything else.
There isn't a LOT that could happen that wouldn't lead to either them surfacing pretty rapidly, or imploding almost instantaneously.