Why does my iPhone 4s get short even after removing the nand carefully

I removed my iPhone 4s nand to remove iCloud but after removing the nand so gently and carefully without any damage on the board, it still got shorted and the pmic become very hot when I try to turn it ON without a nand and it get hot even when I replace the nand..this is the second time it seam when the nand is removed from the board then the board get automatically short. And even with the 1st board I removed all the components that was short even the pmic chip but yet still thier path/pad was short. And please I didn't place the board on pcb holder. I place it on my working table.

So please my question is : was it because I didn't place the board on a pcb holder? or am I supposed to do something before removing the nand? Or nand can't be removed without the board getting short? Or is this thing only with iPhone 4s? I have add the image of the board.