What happened to the reflected wave back to source?
As your cable is a half wavelength long (for a specific fundamental frequency and its harmonics) and the end is short circuited, then essentially the input end of the cable would also be effectively a short circuit, with a standing wave set up in the cable.

What this means is that all of the power from the signal generator would be dissipated in its internal resistance, just like if you shorted out a power supply.