So yesterday morning my wife installed Yosemite on her 2011 MacBook Pro. It worked fine all day until she closed the lid on the laptop and then came to go back on it half an hour later. The laptop wouldn't wake and the light on the MagSafe is flickering faintly. The laptop doesn't respond to pressing the power button at all. When I got home from work I tried everything I could think of. I disconnected the battery, followed instructions to reset the PRAM and SMC but neither of these worked. As my wife needed to use her computer, I removed the hard drive and put it in my 2011 MacBook Pro and she was using it with no issues last night. However, when she came to use the laptop this morning my laptop is now doing exactly the same thing. Can anyone offer any advice on a possible way to fix this as otherwise we've got two bricked MacBook Pros thanks to Yosemite.