My 2011 13" i5/256 did the SAME thing today. It went to sleep ...while the computer was open (went unused for an hour or so)...when I went to wake it, same as you (although, no flickering)...It would NOT come back to life.
I didn't try shutting the lid, I did a hard reboot as you did. First time it's happened to me, and I bought it the day after they released at Best Buy. Not in ANY hurry to give it up though...like you, it took me the better part of an entire day to get it all set up
My Mac Pro had this same issue when I bought it...and shortly thereafter, a patch released from Apple cured it...or, it just never decided to do it again😉 Dunno...I've got a 2010 11" 1.4/128 that's never done this. I'm not sure I've actually every shut that one down (It sits on our breakfast bar at home), with the exception of OS updates that require a reboot. Other than that, it's on 24/7, typically "Sleeping" at night. Never seen this happen. I'm going to keep my eye on my new 13" though.
Other than that...WOW, what a screaming little machine...I'm convinced this is the BEST laptop in the World!!! LOL...after 25 years of buying computers, I'm really...REALLY happy with this little guy.
j