Chosen Solution
Hello guys i bought a macbook pro mid 2012 on ebuy and the seller said the only thing which is broken would be the hdd cable. so i bought a new one and replaced it with ifixit. After plugin everything in again the macbook wont boot at all. The only thing it does it spinning up the fan for a moment and the cd drive makes some noises. I tried to test if its the ram but this had no results. So i holded down the power button 10 sec but it doesnt change anything. The speaker also makes no noises to indicate a problem. Any hints or tips would be really appreciated.
Even without a drive installed you should get some display response: If your Mac doesn’t start up all the way Are you even seeing the display alter its grey color from one shade to another? Does the display have a glow (backlight working)? At this point I would try launching one of the EFI (BIOS) utilities. Restart your system and this time hold the T key do you see a large FireWire or Thunderbolt icon floating on the screen? If you don’t get any response this doesn’t look good ;-{ Reference: Mac startup key combinations
