Got this charger given to me if it was worth repairing.
I found both transistors shorted to zero ohms across all terminals and the resistor blown open circuit.
See the hole in the yellow band.
Don't know what caused it but I reckon it is a throwaway.
possibly, it was dropped and torroid core magnet wire shorted on sharp edge of heat sink, causing chain reaction of shorts. I had similar short between line resistors blowing parts and fuse in garden shear battery charger.