On Tue, 26 Apr 2016 14:56:09 -0500, Jon Elson wrote:

Since the CCU is powered up and communicating with the buttons and
indicators, it is likely OK. Since there was a big POP, and the CCU can't
communicate with the MCU, which is where all the big power circuitry is, it
seems REALLY likely something in the MCU popped. When you get it out, I
think you are likely to find visible damage.

Thank you for that advice.

I'm kind of stuck like a deer in the headlights at this point because
I have to diagnose if it's the CCU or the MCU (or the power rectifier).

I'm kind of at a loss for diagnostic procedures because the diagnostic
test described in the manual didn't kick in.