What causes the HV transistor to blow but nothing else? Samsung k-50

[Sealtest]

Here's an odd question. I am working on a small Samsung tv chassis model k-50 that I got from a closed tv shop. The problem with the set is that it turned on, then off (the lady who owns the remnants of her father's shop powered it up before she could be stopped). This may have been what did the damage but anyways the set blew the 500ma fuse and the transistor for the HV ( Sk9119) was bad. I went through the set and tested Q401,Q402,Q501,Q502,Q202,Q606 and all were good.

So my question is what caused SK9119 to blow when all else is good? In other threads I mention having years of xperince working on vintage hifi gear but it seems that this doesn't convert over to TV repair. With hifi if the main transistor is blown in a channel, or a main transistor is blown in a power supply, there is always a string of dead components. So far that has not been the case with TV sets with me. Do they have more protection or something?