I think the mosfet and power management is integrated type [in the TOP246YN]. [assuming pinouts are the same]
Because you will be dealing with high lethal voltages in the power supply section, are you able to handle it? Do you know how to handle high voltage? What kind of tools do you have now?
If you don't, it would be better to send to the repair shop. [for your safety]
However if you are able then;
What kind of voltages are you getting? It would be helpful to know.
For example;
J2 Pin 2 = ? volts;
J905 Pin 2 = ? volts;
J905 Pin 4 = ? volts;
J905 Pin 6 = ? volts;
J905 Pin 1 = ? [use a logic probe, should be a pulse train at line frequency]
J906 Pin 3 and Pin 4 = ? volts;
J906 Pin 6 = ? volts;
Edit: Then unplug the above connectors and measure the power supply board again. So there should be 2 sets of values for above.