Aaaaand some 6 hours later... and it's baaaack. Didn't change any of the settings they made (all "Sleep" settings) other than logging in with Hotmail/Microsoft account. Came home just now and checked - sure enough, had to hard reset.
So...NOTHING.
Aaaand back already from store - got notification much earlier than expected. Thought it was too soon to be of any use.
Aaaand I was right.
All they did was remove Preview, revert everything to regular Windows 10 that's publicly available, "run hardware diagnostics" which apparently confirmed this isn't a faulty unit, and then tested Sleep a few times.
I was exasperated with the conversation with the person who returned it to me - essentially he said they are aware of the problem, it is less, it "happens sometimes", and there is no known permanent solution ("what do you want me to tell you - they haven't
told us anything else").
So, a load of nothing.
Anyway, for now at least Sleep is working. I guess I will have to assume that the Preview builds were at fault - for my instance at least. And let's try this for a few days and see how many times it happens again.
Sigh. Sorry all - no good news to report.
So I went to a store last evening. Very helpful tech. Admitted they have seen the problem - both sleep as well as battery life - but it has been decreasing since Feb update. Told her Feb update did not help - only worsened. So they have kept it for testing
to remove preview OS to isolate the cause as either software (unreleased OS update) or hardware.
Expect to hear back by Friday evening.
That's very helpful of you indeed, LordZemus. I will try this evening at a nearby store and report back.
Hello everyone, I just wanted to add my experience as it may help.
Like a lot of people here I had the #nowake sleep crash issue on my surface 4. My machine also displayed a noticeable screen flicker when set at low brightness. It had been working up until the Feb 17 update at which point it started failing. I set my
machine to hibernate and followed this thread hoping for some news from Microsoft on a possible fix. I also tried everything to fix it including completely wiping the device and restoring with a factory build several times, not installing various third party
drivers, ect. Nothing worked, my device regularly crashed during sleep. I concluded therefore that this is a hardware problem.