This amp was purchased as a repair/resell item. The symptom was the amp would not turn on. With the bottom plate removed, I checked the PS FETs and output FETs and found no shorts. I input a low V on the B+ terminal and saw no current draw. I checked varies power points, all checked out. Next I applied B+REM and the amp did not build any rail V or draw any current. I checked the turn on circuit and found a burnt 1k resistor.
To verify operation, I jumped with a 1k and the amp powered up. Rail voltage was built as well as output oscillation and output a proper signal.
I replaced that 1k resistor and the amp performed as designed.