White dust on chip pins
That looks like residue from something like safewash water based flux remover. Or residue from washing after using a water soluable flux. The residue is only in places where surface tension would hold water. I'd liberally wash the board in isopropanol (or a similar not-to-strong organic polar solvent) and then blow the gunk-disolved in solvent out with a decent compressed air lance (make sure it doens't have an oiler).

It might or might not be the cause of your misery. The circuit most likely to be compromised would be the crystal oscillator. I'd check your board is getting power, and then I'd check it's crystal is ticking. (If you don't have a scope an old shortwave radio is ideal for checking that)