Input current limit trips immediately. Fix: Desolder the module carefully. Crack it open (use a heat gun to soften epoxy). Replace the primary MOSFET (commonly an IRFZ44N or STP8NK80Z). Also replace the PWM controller IC if its VCC pin is shorted to ground.
Sony MBX-223 (also known as the Foxconn M960/M970/M971 ) is a widely documented motherboard used primarily in the Sony VAIO VPCEB mbx 223 schematic
On the physical unit, you will see rotary switches for selecting crossover frequencies. On the schematic, these are represented by switched resistor networks. Changing the position of the switch changes the resistance value in the filter circuit, which alters the cutoff frequency formula ($f_c = \frac12\pi RC$). Input current limit trips immediately