You are supposed to be measuring the voltage on pins 4 and 8 NOT resistance. Put your meter in the DC volts mode and measure pins 4 and 8. Black probe on ground and the red probe on pin 4 then pin 8. The board needs to be connected to the rest of the amplifier wiring and powered up. I am thinking if you are not understanding this that there is no way you'll be able to repair this amplifier. Replacing SMDs (surface mounted devices) is tricky if you don't have the proper tools, you DON'T. You will end up doing far more damage than the amp has now. My 2 cents with 35 years of experience.
Craig