My MacBook Pro shut down

What kind of machine?

It's not that I'd recommend you do it yourself if you're not comfortable, but I can relay what I did.

I had mine just lock up and I couldn't power it up or power it down. I think it might have been because of one non-Apple, non-MFI Lightning cable that I tried. I heard that they sometimes cause these panics where nothing can be done to shut it down until the battery is completely dead or disconnected. I tried all the stuff including the SMC reset. However, it just couldn't get out of whatever loop it was in. It was really weird too with a faint electric hum I could hear. Other than that - nothing. No display, the MagSafe light wouldn't work, and the battery indicator wouldn't light up when pressing the button. When I brought it into my closest Apple Store without an appointment I was told there were no appointments until a week later or I could try to get on a waiting list the next morning. So I took it home, looked up the iFixit instructions for removing the battery connector, and did it myself. Actually not that bad, and now I'm confident enough to swap a drive or change the RAM.

Right now I think it's really hard to get an appointment for Genius Bar support at an Apple Store since they're being swamped with requests for iPhone battery replacements. But they would probably do this as a courtesy if you could get an appointment.