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It is typical for the TNY264 to blow up. I can see it was real hot.
I can not see if the photocoupler is dead. It should be hard to kill. The black smoke on the coupler may have come from the TNY264. View attachment 115607
I do not have your schematic but here is one that is close.
D5 on my schematic might be shorted. Very typical. That will heat U1 and maybe kill it.
Also D6, C3&R2 might be bad and that will U1.
What seems to be the problem? it is a totally standard circuit. Positive current goes through D1, the circuit, D4, RF1 and back to the supply. Negative current goes through D3, the circuit, D2, RF1 and back to the supply.