Won't wake up: logic board repair needed!
(edited - skip to my own answer below)
Do I have a problem with the Main Logic Board? Maybe the SMC? Or is it something else entirely?
Like so many other have reported, my MacBook Air (late 2010, A1369) doesn't wake from sleep. And when it starts from cold, the realtime clock is reset (to 1 Jan 2000).
When it is asleep, attempts to wake it (keyboard, trackpad, open and close clamshell) seem to have no response. After perhaps 20 seconds, the fan starts spinning at full speed (and the CPU gets hot), but there are no other signs of life. It will stay in that state for at least 30 minutes; the only thing that has any effect is a forced shutdown. It doesn't seem to matter if it is running on batteries or power.
After lots of reading, and trying every purported solution I came across, I am suspecting a problem with the SMC, or perhaps some other part of the main logic board. I've run Apple Hardware Test and found nothing. I've done a SMC reset. I've reinstalled OSX (Lion, but I don't think that matters). I've set the startup disk. I've deep-cycled the battery. I've opened the case and blown all the dust away. I've removed the battery and reinstalled it. I've tried various settings for pmset -a hibernatemode. I've deleted sleepimage. And plenty more beside...
I think I've done everything I can reasonably do, and it looks like a hardware fault - probably with the main logic board (MLB) and quite possibly with the SMC. Everything else seems to work fine. (I would be getting errors about the clock being set to before 2008, except it is finding my WiFi network and running nntp fairly early on in the boot process).
Before ordering a replacement main logic board (or sending this one to be fixed), are there are any other tests I can run, or things I should look at?
My own answer:
Yes, the board need repair.
I followed the instructions here on ifixit, and had a close look.
Imagine my surprise when there was an actual bug pressed up against the SMC (the orange thing at top left of photo). Even if it was not the actual cause of the SMC failure, it makes a great story.
I packed the board up and sent it to a company in China (trading as macexpert on AliExpress).
They repaired the board, for about 200 dollars all up (including postage in both directions). They didn't actually tell me the SMC had been replaced, but it was definitely my board that came back and the SMC was subtly different (although you can't really tell in the second photo).
So... yes: logic board repair needed. And if you're an ifixit sort of person, you don't have to pay the extreme Apple-authorised-repairer prices. Another ifixit success story.
Is this a good question?