I am having a very similar problem. My Surface Pro 4 was having this issue before the Feb 17 update and it is actually happening more frequently since the update. Before the update the Surface would not turn back on maybe once a week or so, but now it does
it almost daily.
I have not had to resort to the volume up and power button fix yet. Usually I have to disconnect the keyboard before holding down the power button for 15 seconds or so to get it working again. However, it often takes a couple of tries before it comes back
on.
I am still trying to figure out what the Feb 17 update actually did, because on my Surface Pro 4 nothing was fixed (display driver still crashes, screen still flickers occasionally, WiFi sometimes disabled after coming out of standby, sometimes the battery
still drains overnight) and a couple issues are worse than they were before. Hopefully it is just me.
Sadly these ongoing issues are why I do not recommend getting a Surface Pro 4 to my family or friends. I have been telling them to wait until the major issues are fixed or get a different computer.
I called ms support and the support tech told me to turn hibernate off.
I had the power button and cover closure configured to use hibernate.
I just changed the above to sleep.
I am not sure if this will help.
I just know that my problem started after the Feb. 17 update.
I have not had the other problems you listed(screen flickering etc) but I just got my sp4 in January so maybe they had the other problems fixed by then.