Redundancy in case power module fails

I am using pixhawk 2.1 and I am using a power brick mini along with the setup. Since my hexacopter setup is consuming 45 A on an average and flying with the brick mini seems to be risky as it has a continuous current capability of only 30A, for that, I have ordered mauch power module but it will take time to reach to me, for time being I need to make a flight.
Since there is a chance of power module failure, can anyone suggest me a way such that in case if the power module fails but the motors still gets the power?
Any circuit design or idea will be appreciated.

You can use any generic 5v BEC and plug it into the motor output rail as long as none of your escs are also outputting 5v (just remove the center red wire from the esc plugs)

It depends on the flight controller.
Pixhawk1, you can provide backup power from the servo rail.
Cube, there is a secondary power input, and no backup power from the servo rail.