The Inport component is typically used to define an input to a subsystem or to a PLECS Blockset model. Since this is at your top-level schematic, and not within a subsystem, you should not use an Inport, but rather a Constant or mathematical function that defines how the current varies as a function of time.

It's also worth noting that you're using the PLECS electrical domain to simulate a thermal circuit. Please be aware there is a thermal domain where you can construct thermal circuits using Thermal Resistors, Thermal Capacitors, and Controlled Heat Flow components.