Chosen Solution
Ever since I replaced the thermal paste on the system board (see “reflow” procedure - very involved and requires completely removing system board from laptop - all cables removed, etc.) my laptop hasn’t been sleeping on lid close. It will sleep if I select it from the menu, or eventually as part of the Power Saver prefs, however. Is it possible I left a cable loose and if so, which one is it? Could this be fixed by a pram reset? Anything else to look at? It’s been running great with new thermal paste, no longer panicking on video issues. Thanks!
The HD SATA cable holds the Hall Effect sensor with the IR sensor. I would recommend you first try replacing the cable MacBook Pro 15" Unibody Late 2011 Hard Drive/IR Sensor Cable Replacement hopefully you didn’t damage the logic board.
