Why does my 700 Series Marine Stereo turn on then off when I First Enable the 12V Power Source?

Fusion stereos have a power state recall feature, which means that when you disable or disconnect the 12V power from the unit it will resume in that state when the 12V power supply is resumed. The stereo will go through a boot up phase much like a smart phone or computer does first, then it will either go into standby mode or become active (dependent on the state when power was removed).