Terminology
Manual reversion means that muscle power only moves controls through mechanical connection between the steering tools and the control surfaces.
This sort of steering does not exist anymore in any big modern aircraft!
Always there is need for some sort of power system to drive the control surfaces - usually hydraulic power.
Moving the steering tools delivers a signal to the powered actuators to set the control surfaces.
Now you get the distinction between conventional control systems and fly by wire:
Conventionally, the position of the steering tools is linked mechanically to the actuators.
With fly by wire, the steering tool position is one of the parameters that is used to compute the required control surface position and electrical wires are used to transmit the command to the actuators.
Mechanical backup is not the same as manual reversion! Mechanical backup still needs (hydraulic) power to actually move the controls.