take pics first. with any luck, the reverse protection diodes took the juice, and they are probably right there by the terminals, which would be where you could possibly see any flame. if there is burning from the heatsink area, the power supply is def. toast, and you are just making it worse, as mentioned. if you have an ohm meter, then you could see by placing it on the terminals, and it should only have constant continuity in one direction. clipping the diodes one at a time, would open the circuit, and show you a little hint how bad the power supply is. as it sits, the flames say that you need to send it in for repair anyways. this will just give you a hint of the damage.