Hmm, do you know where the burnt resistor 'goes'? I.e is it from gate to ground, gate to +ve terminal of a capacitor, or what? On the other bank of unfried fets can you find it's equivalent?
This sort of repair usually entails a certain amount of circuit tracing. If the traces are hard to follow i tend to use an audible continuity meter.
I'd guess the opto isolators are cooked if they were passing the current through the gate resistors; but the good news is the damage is unlikely to have spread 'upstream' of the opto's, which makes it more likely to be a successful fix.