So we're actually really good at enforcing circuits and components against atmospheric pressures. Also they run relatively low voltage. As an example I can imm

So we're actually really good at enforcing circuits and components against atmospheric pressures. Also they run relatively low voltage. As an example I can immediately think of the Compatt devices, they're tested and proven far beyond 4Km depth, and they come with a few options of power supply. They have their own independent power source as you would expect, but depending on the configuration can pull from the device / vehicle. The v4 of the Compatt also comes with extensive warnings around the power draw in relation to reserve so if for example they left and it was only on battery-power for some reason, it will start screaming. The fact that from reports (obviously we don't know for sure) they went at the same time, sadly Occam's razor. Edit : Disclosure : Worked on firmware for off-shore drilling rigs with devices measuring the vibrations and resistance of material being probed for viability.