BMW Will Not Crank or Start Out of No Where

I drive a 03 BMW 330xi, I recently changed the engine in it because my old engine had 2 coolant leaks and overheated and killed itself. The new engine was perfectly fine. Note that i had a leak on my power steering reservoir but i sealed it. I was driving one day and all the sudden the battery warning light turned on red, my trans screen went blank and only the trans warning sign showed up. As i continued my drive the shifts were very rough. once i parked and started the car again, nothing happen, no crank or start. The red battery logo is still there and the trans screen shows the letter S. I have no clue whats up

BMW Will Not Crank or Start Out of No Where