Overvoltage failure modes/PCB repair
If 3.3V was the intended supply voltage, I'm guessing that you didn't have an in-line regulator to many of these ICs.  I try not to design circuits without some sort of regulator for exactly this reason.  Also, you can design in Zener diodes with an inline fuse, or other forms of protection to try to prevent this.

However, it happened, and for finding damaged components, nothing beats a thermal camera.  In this situation especially, you've got components that are trying to pull too much current.  They will be hot.  You can pull them off one at a time until your current consumption stabilizes at what you would expect.

What kind of thermal camera?  I really like my Fluke TiS ($2k from Newark), but you can also get models that are intended to be used for your phone for less than $350.

Shorts from supply rails to ground are more difficult.  You can find these typically by pushing 1A through the supply rail, then probing different vias to ground on the board and looking at the voltage differences around the board.  This will help you find where on the ground plane the current is entering.

Good luck!