From what I observe, the PWM is damaged, usually when they are damaged they explode, what I have used the most is the TNY275P, but I don't know if it will be your case, however I attach the datasheet of the component that I speak to you.
tny274-280-4065.pdf [1.00MB]
Another thing you can do is to raise the diagram of your source and see the application of the component that I mentioned and if more or less it seems you can use it. regards