The key cylinder has nothing to do with power...

The key cylinder is connected to this:

More Information for STANDARD MOTOR PRODUCTS US240T (rockauto.com)

This is the 'ignition switch' and they go bad a lot. When mine went bad the power windows and I think radio wouldnt work - along with a few other weird things I cannot remember. Have you looked at this?

 

The power gets distributed by the key cyl so I would say it does have to do with power, although not directly. When the little bar that activates the key in buzzer Is loose inside it can send power where it shouldn't be. I have the factory shop manual which without would have made alot of what I have done impossible. As I stated I have already purchased a new one.