Broke Hot Water Heater in Roca Azul

Here's a picture. The top is the hot out and bottom is where water enters per the Atwood manual. The By Pass valve is in the by pass position per Winnie. But, when we turn on the pump, the tanks starts filling. I think I see why it does that looking at the pipes...but that is how it came from Winnie. Maybe there is a check valve on the hot side...and it failed? I'm confused. Goal now is to be able to use water. We can heat water/use CG showers.

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