[Spirit_RE]

Bump for posterity:

FINALLY had the chance to get in there and look to see what was wrong. Basically, I didn't re-tighten the set screws enough when I put the new switch in. I slightly changed my technique and used my left hand, which doesn't seem intuitive, but it was easier to reach the 'far-side' screw. It's still a pain in the ass, but I found using the head piece of a hex-insert screwdriver worked the best. One thing to note is that turning your phone sideways and placing it across the clutch & brake pedals provides a good mount for the built-in flashlight to illuminate the under-dash area.

Now everything is working as it should. Lights are turning off and the radio turns off when the key is turned off.