Shinjiikarii

Hello, Just purchased a 2007 Impreza 2.5i, it came with the stock head unit which I quickly swapped out for a Sony car stereo I purchased new from Crutchfield. Install was easy, wired up the harness, plugged the ground back into the bracket, radio works great, no issues at first. After a day I get in the car, go to start it up, as soon as I turn the key to the “on” position I hear a click and all electrical in the car ceases to function, completely dead. So I pop the hood, disconnect the negative battery terminal then reconnect, Immediately everything works just like nothing had happened. This has happened several times over the last couple of days. Anyone encountered this issue before? Any idea what may be going on? Any help would be greatly appreciated.