Thanks a bunch for your reply and kind attention. The problem seems to be fixed, though a bit of mystery still remains. Couple additional details: it was really hot in NY City yesterday, about 90F in my room. So, I thought it could be a thermal shut down. I took the unit closer to air conditioner to cool it down, then I re-charged it, and - bingo! It's running again.
Btw, at the time of this event happens, I was working on that well-known to our CP community Engineering Calculator VOLTA
]. The latest release implements borderless WPF and plenty of other stuff (Online Manual
]) I should probably give away couple hundred free copies of calculator to celebrate the happy-ending of this HW ordeal,.. or at least, to publish couple articles on CP :)
Anyway, thanks again and have a gr8 weekend.