Water damage , dead short across battery

I am currently working on a Samsung Galaxy Grand Prime with liquid damage. I don't know exactly what happened to it, but it was dry when I got it with a decent amount of white residue on the board. The phone did not power on at all. I have removed the visible residue with isopropanol and still nothing.. My multi-meter shows a dead short across the positive and the negative of the battery connector on the main phone board. Any suggestions are appreciated, thank you