I have a 2011 MacBook Pro. About six months ago it developed a sleep problem - it wakes immediately on sleeping. Occasionally when recently rebooted it will sleep as it ought, but usually not. On each waking, the log says this:
localhost kernel: (AppleACPIPlatform) Wake reason: ?
I've done all the obvious things (network, bluetooth, USB) and tried to reset PRAM and SMC, though the latter doesn't seem actually to reset.
More info which might be relevant - occasionally when the Mac is powered off and I plug in the charger, it boots.
Last week the original HD failed and I had a SSD installed. I also upgraded the OS from Snow Leopard to Sierra. The fault has persisted through both these changes. This leads me to wonder if this is a hardware issue.
Only other info about the machine is that it suffered the degrading-solder problem common to 2011 MacBooks. Since it happened before the Apple Repair scheme kicked in, I had it resoldered by a third-party.
Thanks for any help!
Edit: Further to this: a few things I've found: a process called 'hidd' is listed as Preventing Sleep in the Activity Monitor. Its parent is called 'launchd (1)'. And
pmset -g assertions
gives the following:
Idle sleep preventers: IODisplayWrangler
And finally - when I put the computer to sleep, it very briefly sleeps (1s or so), but then HD starts up again. The sleep light goes off, and does not wink or re-light, but the display stays off. To 'wake' it again takes 10-15 seconds.