Just as an update: the problem persists with mine, but I have learned to live with it for now. Mine is definitely having issues with the ribbon cable and/or the hinge around which it goes, but careful handling is a kind of workaround for now.
I avoid closing it now unless I need it in my pocket, after which I generally need to open it slowly and smoothly at least twice before it will stay lit all the way to fully open. On the first attempt (or two), it will light as it starts to open, but then blink out around halfway to two-thirds open. It will do a bit better on each attempt until it finally stays lit through the whole unfolding process, and is fine after that.
Ironically I just made my final payment on it last month. 🙄 I did try visiting an official Samsung repair facility in Algonquin, IL to get a quote, but after some button clicking on their terminal, they announced that it would cost me $406 (an oddly specific amount), which ain't happening. (They were similarly unhelpful way back in Year 1 of ownership when the Power button got stuck down, announcing that they would not fix it under warranty due to "dropping," which never happened, but good luck proving that. Their whole purpose in life seems to be turning away people needing repairs to their phone.)
I'll probably go with the Flip6 soon, as I did get three very good years out of this Flip3, and the folding feature proved to be as useful as I had hoped. I normally keep my phones until their outdated software makes them utterly obsolete (my Galaxy S III) or they suffer some kind of internal stroke (my S7 Active), but in this case I'll probably take advantage of a trade-in offer soon and let them have this one back.
