Not to be pessimistic or trash your thread...But by looking at an electrical failure with out a microscope and proper diagnostic equipment you cant possibly properly diagnose the problem. Just by looking and seeing that the transistors had lit on fire may mean there are more problems, How did the transistors get over heated to the point where they ignited? Sounds to me like a voltage regulation problem or a short. now with that said you have two possibility's a resistor may have failed flooding the circuit with an unregulated amount of voltage and ohms damaging more than just the resistors. Now remembering that all the electrical components are connected so you have to trace from where the problem started to where it ended and fix all the problems. Another problem with a board that has ignited is "de-lamination" This is where the inner part of a circuit board starts to measle and bubbles and comes apart like pieces of paper which can damage ground planes and actual printed circuitry. Thats just my two cents...Take it for what its worth.