Bad news.
In my setup doing the ON-OFF-ON cycle is NOT enough ...
Switching off the battery is enough to blacken the radio displays, but switching it on again is not felt ... by the MCP & the radios, that is the CPFligth modules.
I also experienced "bad manners" by the MCP.
It does reset KIAS value to "100" even after I have set it to V2.
It does reset the XPDR to "1200" even after I have entered the code.