After replacing the speedometer bulbs and reassembling the dash the radio does not work?

Maybe my new/used 2001 PT Cruiser is possessed? After two days of trying every trick, I know (including testing and retesting fuses) the radio refused to show any life except to display the "time" when prompted. I finally decided to replace it with a similar radio from an old 2003 PT Cruiser, but even though that unit was similar the wiring harness was different and so I returned the dead radio to its place, reattached the wires/power/grounding, found it was still dark (except the "time" feature) and so wrote off the project as a lost cause. An hour later I returned and turned the motor, and - against all logic - the radio dial lit up, with factory preset signals (such as 530 khz), and the LEDs glowing on the equalizer. Then before my very eyes my own previous resets returned to the dial. Everything works fine: radio/cassette/CD. I have no idea how to explain this. I did leave the ignition key in the "on" position (without cranking the engine) for that hour in the hopes of rebooting the vehicle's computer. I am happy it is working - it beats one local Chrysler dealership's offer to "send it off" for analysis at $200 (plus repair costs) for a minimum of two weeks. All the fuses were fine, so that was not the problem. The ground was tightly attached (like all Chryslers I've owned it doesn't ground very well, engine static on the AM band). I would love to hear your best guess at what gives.I chose your site because of the superior technical knowledge in your answers. Please don't suggest this PT is possessed.I know nothing about previous ownership and the name "Christine" is already taken.

So far so good! Many thanks for all your advice!