Check Charge System-Honda?

I drove home in my Honda Fit Sunday evening. It has 143k miles and drove 43 miles home, my commuter vehicle. Come Monday morning the car would not start. I have a battery scanner, it told me the battery was operating at 30% capacity but was still holding a charge at 12+ volts. All electrical components seemed to turn on. When turning the key, the starter would not respond. I drove my gas guzzler to work that morning. I attempted to start the Honda Fit again in the afternoon and this time the starter responded but the engine would not turn over. Dash error reads “check charge system”.
I bought a new battery and cleaned both the positive and negative terminal connectors. Same issue. I checked all fuses, in the engine bay and under the steering wheel, all were good. I replaced the negative battery terminal sensor(used) but no change, same error. I replaced the negative wiring terminal and cleaned the grounding point to the car with a wire brush, no change. I verified the positive terminal was getting power with the key turned to the on position. The fit has 3 large fuses on the positive terminal, seemed to be working fine without and visible damage. Multimeter stated voltage was fine. Car will not shift out of park. I gave up and had the car towed to a shop.
They tested the alternator and starter, both are getting the correct voltage from what I’ve been told. The car has been in the shop about a week and the mechanics have yet to find the issues.
My next step would be to have it towed straight to Honda and give up my kidney to pay for the repair costs. Does anyone have experience with this issue?