Answer to "What’s my issue: I/O Board, I/O Board Flex Cable or Logic Board?"Hello guys, I had the same problem. So I bought the model a1466 from a friend and decided to repaste for better thermal. I was done and forgot to put back the io cable. The fan starts and stops starts an stops again and then its boots up. No sound, fan goes crazy to 6000+ rpm if im not mistaken. If i connect the io cable the laptop whut instantly shut down. The laptop would still charge but the charger will not show any led color. My problem was that i put the io cable wrong. After doing that it was fixed. Dumb mistake, costed me 25$ as I already bought a new cable.