I can share the story that happened to me yesterday.. man, that was crazy.

I bought a used WPC power board and wanted to test it on my Shadow.
I put the original power board down, installed the "new" one, connected all connectors, powered it up and bam.. fuse F104 blows!
Ok, I said.. There's something wrong with this board. Put it back down, inspected it and found one TIP102 transistor is shorted.
I had a few TIP102 in stock but didn't wanted to do the fix at that time so I decided to put the original board back on.
BAM!! Fuse F104 blows with the original power board. One hour ago I was playing it. Probed the same TIP102 on that board and it was shorted! An hour ago I thought I had 2 working power boards and ended up with broken machine and two broken power boards.
It was a depressing moment.
Why did the original power board's fuse and transistor blew? I was asking this myself for hours.
Stayed up until late in the night, reading the manual and wpc schematics, probing everything and the only thing that was connected to this F104 were low power coils. Then it striked me. It must be a blown coil. Tried measuring the resistance of all coils.. all between 3 to 10 ohms. All fine.
Hmmm. I knew I won't be sleeping that night. And then my friend, who I was sharing this misery with, reminded me that we didn't checked the little coil that stops and let go the wall target... And then we found it.. SM-30-1100-DC, small little f*cker that blew/shorted after I connected the new/used board. Later I noticed that instead of 3A fuse in F104, there was 8A fuse in it!

Then is put everything together..
The new/used board was cheap because someone thought it doesn't work. This person had a coil shorted on his machine and every time he powered up the machine, fuse and transistor blew, he then thought that 8A fuse may help, but it didn't and every time he ended up with a blown fuse and a transistor. A bit PITA.
Somehow I got this power board with no story... tried it, fuse, transistor AND also my wall target coil blew up and shorted. Put my original board in, powered on, same story.. Everything blows because of the shorted coil.

Well, I have this coil disconnected now. Waiting to get a new one.

So the point of the story may be.. be careful with what you put in your machine. Check for shorts and stuff, so it doesn't blew your working parts away.
Btw, why is TIP102 blowing up. Shouldn't only the fuse blow up?