Swapped engine was running then all of the sudden squeak and no crank no start?

So I purchased a car and the next day I spun a main Bering. So, I swapped the engine for the same engine but a year newer. After I got done, I started it, and I was letting it run at idle to observe. While doing so out of nowhere I hear a “squeak”, and the engine shut off? I try to start it again and nothing I hear the starter “click” and nothing.