I did the EXACT same thing after replacing all my ribbon cables with new ones. I put the old ones on and I had power back except the flippers didn't work at all. I reseated all connectors at least 3 times and it didn't help. I was sure I bent a pin or something. I friend who knows pinball machines 1000 x better than me looked and in ten seconds saw I had one connector off a pin or something. He reattached it and it worked.