Detecting loss of power redundancy, or sudden boot on only one 5v supply

I found a faulty Mauch PowerCube 5v output in one of our big/dangerous/expensive multicopters when checking why an non-critical onboard system was dead.
Simply put: one of PowerCube’s 5v outputs died, and the Cube would have flown just fine - booting, and being oblivious to the fact that it was powered by only one 5v source.

Is it possible to detect that you have a single 5v source using telemetry ? - (not only if the power selector IC switches, but if booted with only one 5v line…)