The power transistors shorted first. The resulting high current burns out the emitter resistors. If they are designed to fuse they will look perfectly normal but measure open. You may also have a bad rectifier, or perhaps the resistors havent fused yet if you are also blowing fuses. There has to be a current path… somewhere… to blow fuses. Do a health check on the rectifier, all output transistors, emitter resistors, both drivers, and every single component that connects in between the bases of the driver transistors (aka the bias network) on any channel that’s affected before proceeding further.
