yep that's it

if it has locked on then there are problems else where in the circuit also. you will need to find out if the IRL540 has gone short.

you would need to test if any of the diodes or transistors have failed.

I can see a design fault on the aux driver, if the wire from the display board in the schematic has a bad connection or becomes loose there is no pull down resistor on the gate of the Q3 and it will end up killing the transistor.