Any idea where the C4131 and A1745 transistors are located on the board?
They are on the main board. They are larger transistors that are attached to a big heat sink. It's biggest thing that sticks up off the board.
I would also suggest testing the fuses again. A lot of times what happens is the fuse pops, you replace it, and then it pops again because the root cause wasn't addressed. Check all of your cable connections and air dust them. Make sure every cable is plugged in straight and there aren't any bent leads. Replace any questionable cables.
Also, never work with the machine plugged in and when you do unplug it, wait 15 minuted before working on it.
At the end of the day, if the fuses are good and you still can't get it to fire, the head is most likely fried.