Hey!
First you need to run a flow volume extraction operation. This will generate the flow domain and remove all solids from your geometry.
Afterwards, you’ll have to re-mesh. Also, doublecheck your velocity inlet boundary conditions. They’re different from each other.
Lastly, I don’t see any heat source in your project right now. You can set them via boundary condition (Wall BC, some sort of heat flux for temperature) or via Advanced concepts > Power sources).