What other hardware have you got connected to your A1200?
Plug in a RAM module (I don't think it matters which slot, but try the slot which is flush to the PPC card first) and turn on the A1200 with nothing else attached - just the A1200 mobo and the BPPC. Try another RAM module if possible just in case the RAM is bad.
What I don't understand is why the fan doesn't spin. Even on a dead PPC card the fan would still run as long as it's getting the correct voltage. Ty a different PSU? Is your A1200 towered? You can splice a cable from the PSU directly to the PPC fan instead of using the little power cable that plugs into the PPC card.
If you hold down both mouse buttons when turning on the Amiga, can you see the early startup menu? If so does the BPPC show up as working in Expansion board diagnostic?
You can try to hold down the Escape key instead of both bouse buttons after powering on and see if you can get to the BPPC menu. Try altering the RAM settings.
How is the motherboard powered? If it's in a tower and you have an ATX or AT PSU, try powering the motherboard from the original power connector at the back, and plug a 3.5" power connector from the PSU into the floppy power connector from the motherboard at the same time. It could be that the PPC card is just not getting enough power to work.
Try removing the heatsink from the PPC and check if there's any dust under there. It gets dirty quite easily. Clean it, apply some Artic Silver paste (just a small amount) and replace the heatsink.
If you still get a black screen after this then it's 99% certain that your PPC is f***ed. If you're a gambling man then you could send it to DCE, but otherwise, the guy in France seems to be "The Man".