[philso]

The board that rsegrest posted is a slightly different version from the one shown on page 35 of the User Manual on the TI website. The damage is consistent with an excessively high current passing through the current sensing resistor, R35, causing it to vaporize itself and some of the adjacent copper track. Since there is no visible damage to the MOSFET's, other than soot from the exploding resistor, it is not likely to be a shorted load that caused the fault current. It is likely that some conductive particle fell in and shorted some adjacent pins on one of the chips causing abnormal operation, say turning on both the upper and lower MOSFET's. This would make the MOSFET's try to short out the incomming 12 V supply. It is possible that the particle to have fallen in some time ago and lodged itself in a "benign" location then moved to where it could cause the Magic Smoke to be released.

Conformal coating is for environmental protection and is not normally considered a proper insulating material but at 12 V it is probably effective enough to make a difference.