hardware problem causing MB pro 2012 to not awake from sleep

[mlsimmons]

I have a 13" mid 2012 MB pro - i7, 16GB that has started to not awake from sleep after closing the lid. I have force quit it, reset the SMC, and the PRAM multiple times. I have taken the bottom off , reset the memory, unplugged the battery and it won't reboot. It has restarted only 3 times since experiencing the initial problem. Once when the lid was closed and I plugged the charger in I got the startup chime and when I opened it, it ran fine as long as the lid was open - when I closed the lid, it went to sleep and just sat there with the white blinking light no matter what I did to try and wake it - when I forced quit it it wouldn't do anything when I pushed the button to start it. It has booted two other times, once after resetting SMC where I got the double startup chime and another time after it sat overnight when I pushed the power button. again when I closed the lid it stayed in sleep mode. on one of the occasions where it booted I ran Onyx to reset the system and clear the cashes, and reset all the energy saving preferences. It is not hooked (or ever has been) to an external monitor. I have even replaced the hard drive with one from a working identical machine and nothing changed. Is there some mechanical switch (magnet or otherwise) in the lid or part of the hinge that could have failed or shorting out that is causing this to happen? like I said when it boots it runs flawlessly